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5 Most Important Battles of the Civil War

Eric enjoys exploring historical events, and has a particular interest in the Civil War and early American history.

Cannons at Antietam National Battlefield. The fight at Antietam (Sharpsburg) was one of the most important battles of the Civil War.

Cannons at Antietam National Battlefield. The fight at Antietam (Sharpsburg) was one of the most important battles of the Civil War.

The Civil War

For most Americans, the Civil War is a hazy period back in the seemingly distant past. The general history may be clear, but specifics are hard to fathom from our present-day perspective. The idea that our nation could literally break in two is almost impossible to imagine, as is the fact that, had events played out differently, we might be living in a very different world today.

The Civil War began with the Confederate attack on Fort Sumter, on April 12, 1861, over 160 years ago. While many aspects of society and culture have changed, it’s important to realize that the hopes, dreams, and aspirations of Americans back then were very much the same. The destruction of the United States was then, as it would be today, unfathomable and heartbreaking.

However, as terrible as this war was, it may have been the necessary evil to bring about a change that had been simmering for decades. The Union emerged victorious in the end, but there were certainly times during the course of the war where it appeared a Confederate victory was achievable.

While it is important to consider that every battle that occurred during the Civil War was influenced by events that came before it, there are still those watershed moments where, had they played out differently, the Union as we know it may have been shattered. These are the most important battles of the American Civil War.

5 Major Battles of the Civil War

  1. First Battle of Bull Run (First Manassas)
  2. Battle of Glorieta Pass
  3. Battle of Antietam (Sharpsburg)
  4. Battle of Gettysburg
  5. Siege of Vicksburg

Note: These events are presented in chronological order and not necessarily listed by order of importance.

Some naive Northerners believed that the First Battle of Bull Run would be the first and final battle of the Civil War. They were sorely mistaken.

Some naive Northerners believed that the First Battle of Bull Run would be the first and final battle of the Civil War. They were sorely mistaken.

1. First Battle of Bull Run (First Manassas)

The First Battle of Bull Run was the first major engagement of the war. It would be, some in the North believed at the time, the only battle of the war. Confederate forces were green and unorganized compared to the Federal Army, they reasoned, and all that was needed was to plow through whatever little opposition they offered and take the Confederate capital of Richmond.

It was with this goal in mind that a Federal army, under the command of General Irvin McDowell, marched out of Washington on July 16, 1861. The first phase of the campaign would be to attack the Confederate Army of Northern Virginia amassed at a creek known as Bull Run, thus allowing troops from the larger Union Army to flank and destroy the Confederate line.

Astonishingly, many civilians followed the U.S. Army on their march from Washington. Expecting a speedy and decisive Union victory, and the quick restoration of the country, they didn’t want to miss out on the action. Citizens, some in fancy carriages and packing picnic lunches, hoped for an entertaining expedition. Instead, they would get a terrifying reality check.

The battle that erupted on July 21st was messy, disorganized and brutal. McDowell’s Union force consisted of a large number of volunteers, who had yet to acquire the discipline and communication skills needed to execute military commands. The Confederates, under the command of General P. G. T. Beauregard, were no better, and much fewer in number.

At one point, superior Union forces broke the Confederate line and sent them into retreat, but reinforcements under the command of General Thomas Jackson reinforced, stopping the Federals in their tracks. This earned him the legendary nickname “Stonewall” Jackson and rallied southern troops to mount a counterattack.

Jackson’s forces surged forward and, along with support from Confederate cavalry led by MG J.E.B. Stuart, captured several Federal cannon batteries. Forced from the field, the Union army retreated back to Washington, their throng of stunned civilian onlookers in tow.

The First Battle of Bull Run is significant because it severely altered the perception of how this war would unfold, for both the public and the Federal government. Like an underdog boxer, the Confederate Army of Northern Virginia had sent its opponent to the mat in round one, making it clear that this would be no easy knockout. Indeed, the Civil War had many rounds to go before a winner emerged.

2. Battle of Glorieta Pass

The far western reaches of the United States were still young and unsettled at the time the Civil War broke out. The issue of slavery was a major point of contention as the western states and territories took shape. Heated debates raged, both in the east and west, between those who would wish to see the west free, and those who wanted to expand slavery to new parts of the country.

Most iconic Civil War battles took place in the east, between massive armies and tens of thousands of individuals. But one small but important fight at a place called Glorieta Pass, in what is now the state of New Mexico, went a long way toward keeping the west out of the hands of the Confederacy.

Soon after Southern states seceded from the Union, a part of the New Mexico Territory broke off and allied with the Confederacy. Known as the Confederate Territory of Arizona, the significance here was twofold. Firstly, the Arizona Territory offered a real Confederate presence in the west. Secondly, it provided a corridor between the Confederate state of Texas, and California with its ports and bountiful land.

A Confederate force called the Army of New Mexico, made up largely of units from Texas, began the march toward California and the Colorado Territory, winning several battles along the way. It’s important to remember that the Union Army, as well as the United States government, had their hands full with fighting in the east at this time. U.S. Army forts in the west were understaffed and ripe for plunder. Taking control of a trail called Glorieta Pass would allow Confederates an easy assault on Fort Union to the north, and a relatively unopposed path westward.

On March 26, 1862, Union forces under the command of Col John Slough and Maj John Chivington, a former preacher, engaged the Confederate Army at Glorieta Pass. Fighting on the first day came to a stalemate, and the second day saw little action, but on the third day, the Confederates forced a Union retreat from the field, allowing a clear shot at the trail.

However, during the melee of the battle Union scouts had managed to locate the Confederate supply wagons. Union troops snuck behind the Confederate line, destroyed and looted the wagons, took prisoners and killed or scattered the pack animals.

Although the Confederate Army had won the fight, they were left without food and supplies. They had no choice but to retreat back to the Arizona Territory.

The Battle of Glorieta pass is sometimes referred to as the Gettysburg of the West, in the sense that it helped determined the outcome of the Civil War. That may be an overstatement, but it is easy to see the importance of this battle, and the potential impact had it gone differently.

If the Confederates had been able to take Fort Union they would have gained a solid foothold in the Southwest. If they were able to take, and hold, parts of California the Union naval blockade in the east would have been largely nullified. And, with almost endless resources to bolster them, the C.S.A. would have been able to supply their war efforts for the foreseeable future.

Worse, with many pro-slavery sympathizers already stippled throughout the west, it is even possible that a Confederate presence may have encouraged more states and territories to secede from the Union.

The West during the Civil War. Note the strategic significance of the Arizona Territory.

The West during the Civil War. Note the strategic significance of the Arizona Territory.

3. Battle of Antietam (Sharpsburg)

By September of 1862, the Federal Government and President Abraham Lincoln had become increasingly frustrated with the war effort. Losses mounted one after the other, and morale waned. The Federal Army of the Potomac, under the command of General George McClellan, had proven incapable of crushing the Confederate Army and putting down the rebellion.

The Confederate Army of Northern Virginia had a new leader, as General Robert E. Lee had taken command in June. Within months he launched a bold campaign to invade the Northern state of Pennsylvania and the border state of Maryland, with the goal of cutting off the railway routes to Washington. With the Presidential election looming, and Lincoln’s popularity fading, Lee reasoned that making life miserable for citizens in the North might encourage them to elect a new government, one willing to end the war and leave the Confederacy alone.

Lee’s plan involved dividing his army, sending one corps under the command of MG Stonewall Jackson to capture the arsenal at Harpers Ferry, and another under the command of MG James Longstreet toward Hagerstown. Another force, consisting of most of Stuart’s cavalry and a division under the command of General D.H. Hill, would defend the rear. The army would reassemble later, near Boonesborough or Hagerstown, after Jackson’s and Longstreet’s assignments had been carried out.

The Union Army pursued Lee northward in an effort to turn back the invasion. Then, in a twist of fate, the historical significance of which cannot be understated, Union soldiers discovered a written copy of Lee’s marching orders at an abandoned Confederate encampment near Frederick, Maryland. With Lee’s intention now clear, McClellan moved in to attack.

The two armies came together near Sharpsburg, Maryland, on September 16, 1862. The remnants of Lee’s forces numbered less than 20,000. He had recalled Jackson and Longstreet, but until their forces arrived he was severely outnumbered, and could only take a defensive position behind Antietam Creek.

However, McClellan, exhibiting the typical caution and ineffectiveness that enraged President Lincoln during the early years of the war, failed to commit to a full-on attack. He believed Lee’s forces were far greater in number, and was concerned about the possibility of a trap. By the time the Union Army launched its first assault on the 17th of September, Longstreet’s Corps, and most of Jackson’s, had arrived on the field.

The battle that erupted was the bloodiest single day of fighting in American history. Union attacks were time and again repelled by the Confederates, who mounted their own counterattacks, driving back the Federal troops. One location, a simple cornfield nearly in the center of the battlefield, saw especially ferocious fighting and changed hands several times during the course of the battle. Miller's Cornfield has gone down in history as one of the most horrific killing spots of the entire war.

The remnants of Jackson’s Corps, under the command of General A.P. Hill, finally arrived later in the day, and helped stop the final Union attack. The Confederates had held, and the fight was a draw, but the significance of the stalemate reverberated far beyond the battlefield.

Lee’s campaign to threaten the North had failed, and he was forced to retreat back to Virginia. This was a major victory of the struggling Union Army, and a President who, until now, surely had visions of the country slipping away.

Lincoln used the opportunity to announce the Emancipation Proclamation, which (in theory) granted freedom to all slaves in the Confederate states. Still, he was furious with McClellan for not pursuing Lee and destroying the battered Army of Northern Virginia. Lee remained a powerful force to be reckoned with, and he would return to the North in another invasion attempt soon enough.

Each year, on the anniversary of the battle, over 23,000 luminaries are lit at Antietam - one for each casualty.

Each year, on the anniversary of the battle, over 23,000 luminaries are lit at Antietam - one for each casualty.

4. Battle of Gettysburg

While Lincoln claimed victory at Antietam, any hope that it would turn the Union's fortunes in the war was short-lived. Frustrated by McClellan’s ineffectiveness during the battle, and indeed during his entire tenure as commander, Lincoln relieved him and installed MG Ambrose Burnside in his place.

Burnside promptly sent thousands of his troops to their slaughter by continuously assaulting a heavily fortified stone wall during the Battle of Fredericksburg in December of 1862. It was a stunning loss for the Union, and any imagined momentum gained from the fall fight at Antietam was gone.

General Joseph Hooker replaced Burnside who, after threatening to resign, was transferred to the Western theater. Hooker lost at Chancellorsville in the spring of 1863, and Lee’s Army of Northern Virginia once again headed North in an attempt to threaten U.S. cities and put an end to the war.

The Confederate city of Vicksburg, Mississippi, was besieged at this time as well, under duress from the Union Army of the Tennessee, led by General Ulysses S. Grant. Vicksburg was a key strategic point on the Mississippi River. If Vicksburg fell, the Confederacy would lose control of the Mississippi. Another Confederate invasion of the North, Lee hoped, would draw Grant away and relieve pressure on Vicksburg.

Hooker followed Lee north, but Lincoln soon lost patience with his ineffectiveness as well. When Hooker resigned, Lincoln replaced him with MG George Meade. Meade moved quickly and mirrored Lee’s movements, attempting to stay between him and the Eastern cities of Washington, Baltimore, and Philadelphia.

On the morning of July 1st, 1863, Union cavalry encountered forward elements of Confederate infantry near the small town of Gettysburg, Pennsylvania. A scrap soon erupted into one of the most massive battles in American history. Over the course of three sweltering days, the fight raged on, culminating in one final push by the Confederates to crush the Army of the Potomac, and win the war.

On the third day, Lee ordered a full-on assault against his entrenched opponent. After a ferocious cannonade, some 15,000 Confederate infantry troops stepped from the tree line and began the three-quarter-mile-long march across an open field and toward the Union position. Cut down first by cannon, and then by musket fire, the weakening force eventually breached the Union line, getting as far as Union cannons before they were driven back in retreat.

Now known popularly as Pickett’s Charge, this failed attack resulted in thousands of casualties, the loss of the battle, and, some argue, the war. The final push was supposed to have been a three-pronged attack, consisting of an assault on the Federal right flank at Culp's Hill, and Stuart's cavalry riding around the Union position and attacking from the rear. But Union troops held the flank, and Federal cavalry met Stuart, leaving the attacking Confederate infantry with no support.

Lee’s army conceded the field the following morning and staggered back to Virginia. Another Northern invasion had failed.

One point on the Gettysburg battlefield marks the deepest place where Confederate troops breached the Union line. Known as the High Water Mark of the Rebellion, there a monument now stands. This is the closest the South would come to winning the Civil War.

Indeed, many consider the Battle of Gettysburg the turning point of the American Civil War. A Confederate victory here would have gone a long way toward ending the war. And, based on the actions of the previous months, it was entirely conceivable that Lee would have prevailed once again. His aggressive decision making, which until now had been a tremendous asset, failed him when confronted by a patient, tactically clever adversary who was perfectly willing to dig in and let him make the first mistake.

Lee made that mistake, and the failure of Pickett’s Charge cost him dearly. It’s a decision that will be debated by military historians until the end of time, one Lee is said to have regretted immediately after the assault, and for the rest of his life.

High Water Mark of the Rebellion at Gettysburg

High Water Mark of the Rebellion at Gettysburg

5. Siege of Vicksburg

As Lee marched north, Grant stayed put, keeping pressure on Vicksburg. It had been a long slog to get this far, and Grant’s efforts to move on Vicksburg during the fall and winter had not been successful. In the spring, he enacted a brazen plan to march his troops down the western side of the river, cross the Mississippi and assault the city.

Beginning in late April, Union Army and Navy forces led several attacks designed to pave the way for a clear shot at Vicksburg. By May 18, 1863, Grant’s army was at the gates. Though surrounded and with no route of escape, the entrenched Confederate Army and the civilians of the town held out for weeks before finally surrendering on July 4th, 1863.

The fall of Vicksburg came on the very same day Lee retreated from Gettysburg. This one-two punch of devastating wins in both the Eastern and Western theaters provided a needed shot of adrenaline for the U.S. government and Lincoln’s popularity. He would win reelection in 1864, an event that had seemed unlikely up until this point.

But the taking of Vicksburg provided much more than just a morale boost for the United States. The Union now had control of the Mississippi, and could freely move troops and supplies along its length. The future of the Confederacy was now in serious peril.

While there was still much bloodshed after Vicksburg, in many ways it set in motion the events that led to the end of the war. The Confederacy fought on, but Union forces were now able to penetrate deeper south, taking Southern cities and terrifying civilians.

In March of 1864 Grant was promoted to command of all Union armies. As he battled Lee and the still-formidable Army of Northern Virginia, he tasked a friend and former subordinate, General William Tecumseh Sherman, with taking Atlanta. Sherman did, torched much of the city, and began his now-infamous March to the Sea.

By then desertion rates had risen among Confederate regiments, and many in the South had about had enough.

The End of the Civil War

On April 9, 1865, General Robert E. Lee met with General Grant in a humble citizen’s home near the town of Appomattox Courthouse, Virginia, and formally surrendered the forces under his command. The mighty Army of Northern Virginia was now, finally, defeated.

The Confederate capital of Richmond had fallen days earlier, and President Jefferson Davis was on the run with what remained of his dying government. He was captured by Union cavalry on May 10th. The Confederacy was no more, and the Nation could begin to heal. Of course, that healing process would be marred by the assassination of the President who had led the United States through the most difficult time in its young history.

In a better world, difficult changes might occur without requiring the loss of hundreds of thousands of lives, the destruction of cities and the displacement of tens of thousands of families. In a perfect world, the situation that made those changes necessary would never have existed.

As it stands, the Civil War was a huge mountain our nation had to climb over to get to a better future. It is impossible to say where we’d be today if it had gone differently. However, it is easy to speculate that, had certain important battles not ended as they had, the mountain surely would have been much bigger.


  1. Civil War Trust
  2. Civil War: National Parks Service
  3. Civil War: HistoryNet


Eric Dockett (author) from USA on August 11, 2020:

@Andrew - "Patently absurd" seems a little harsh, but I understand your position. However, establishing a stronghold in the west was a part of the Confederate plan, half-baked or not, and turning them away at the Battle of Glorieta Pass made them reconsider this strategy.

Andrew Heller on August 10, 2020:

I might quibble with 4 of your choices, but probably not (although I believe I could make a good case for inclusion of Fort Donelson,) but I am compelled to say that your choice of the Battle of Glorieta Pass as one of the 5 most important battles of the Civil War is ludicrous. Your reasoning, that if the Confederates had won this battle, they would have been able to overrun large parts of California, is patently absurd. The total Confederate force at Glorita Pass was 1300 men, and were over 1000 roadless miles from the coast of California. By 1861, there were 5 regiments of Union volunteers in the San Fransisco area alone, or roughly 5000 men. The Confederate force that finally reached Glorita Pass was at the end of its supply line, and it would have been literally impossible for it to reach California before disintegrating due to lack of water and provisions.

Even if by some miracle these 1300 Confederates could have defeated 4 times their number in California, it would have had exactly zero effect on the war in the East. There was no transcontinental railroad in 1862 when this battle was fought, so how could these "endless" resources ever reach the East. It so happens that the South did have a supply line for arms west of the Mississippi: in Texas. Until the fall of Vicksburg, the Confederates were able to trade cotton for weapons and other goods through Mexico. After the fall of Vicksburg, this ended, as of course would have anything coming from further west (not that there was any way to haul bulk goods all the way from California. Finally, even if the south had conquered New Mexico and/or Arizona, once the Confederate government surrendered, whatever gains they might have made in the Southwest would have reverted to the victorious Union.

Eric Dockett (author) from USA on March 21, 2020:

Thanks for the kind words. I do my best not to disappoint anyone. Good luck with your assignment and try to stay positive during these tough times.

Not Avaliable on March 20, 2020:

I enjoyed, being home-schooled due to a virus, my mum required me to put 5 Civil War battles and this was not a disappointment.

no name on December 01, 2019:

This is a life saver for a quick summery of these battles and great to take notes from.

Thank you.

John Dove on September 27, 2019:

Hi Eric--

The Battle of Antietam was you correctly describe was one of the most significant battles of the Civil War. I argue that it was perhaps THE most important battle as it prevented Lee's Army from moving toward Baltimore, Washington, and Philadelphia. It broke the back of the Confederacy.

Regards, John

Brad Watson - Miami on September 02, 2019:

In 1776, the Northern statesmen were surprised at how fast the Southern statesmen came on the side of rebellion. What was kept secret was how the Southern plantation/slave owners owed million$ to London banks and London markets took 40% of cotton & tobacco profits. A successful revolution would wipe out this debt and move markets to the new country.

In 1860, the Northern statesmen were surprised at how fast the Southern statesmen came on the side of rebellion. What was kept secret was how the Southern plantation/slave owners owed $1 billion to New York City banks and NYC markets took 40% of cotton & tobacco profits. A successful revolution would wipe out this debt and move markets to the new country.

Jdog on August 25, 2019:

A list of "most important battles" without Atlanta is an invalid one. I'd even put Chattanooga in there.

Matt on July 06, 2019:

On 4th of July weekend, wanted to read some American history articles. Did not disappoint.

Max Anderson on May 25, 2019:

I think the Battle of Atlanta should have been included. It cemented the loss for the Confederacy and Sherman did the moping up as he marched to the sea.


Pyper sellers on May 20, 2019:

This artical is awesome. You definitly should wright more articals on history.

Graceful mountains on May 07, 2019:

Thanks for making such a amazing article and I think it is worth reading i am homeschooled and i am currently on history and that’s the last class of the year and your article has made my end of the year project simpler so I might just thanks to you thanks for really doing a wonderful job i hope to see more amazing articles by you

Henry Chaing on March 07, 2019:

This is a very good article.

Anynomus on December 03, 2018:

Great job. I really learned a lot about the civil war from this!

Robert on November 21, 2018:

This article was very helpful because right now I am researching on this topic.

Damian H. on February 12, 2018:

This document is very helpful to me. My class is currently researching about the civil war, and we have to write an essay. This article helped me find my main ideas.

Eric Dockett (author) from USA on September 08, 2017:

@ Ron: I was hoping you'd comment on this. I know you are one of our resident Civil War experts. :-)

You are probably right about Glorieta Pass, and I knew including it would be somewhat controversial. But I find myself fascinated by the possibilities were the Confederates able to defeat Canby in the West. While they likely hadn't the manpower as it stood to hold any major port or city, perhaps both Confederate and Federal leaders in the East may have made different decisions that affected outcomes in the Eastern theater. If the Confederacy made the West more of a priority, the Federal government might have been forced to expend resources they otherwise put into the fighting in the East.

Maybe a stretch, but like I said I am intrigued by the possibility.

@ CJ: Thanks for the kind words. I've been doing some research on westward expansion during the 19th century and became somewhat fascinated by the battle. As you and Ron both said there are surely others to consider, but I do think it was significant.

Ronald E Franklin from Mechanicsburg, PA on September 07, 2017:

Eric, this is a good overview of these five battles. The only quibble I have is with including the Battle of Glorieta Pass. Seems to me that even if the Confederates had won in New Mexico they simply didn't have the resources to extend their reach in the West. Plus, after Vicksburg was taken, the Trans-Mississippi became largely irrelevant. Even if supplies could be freely brought in through California, they couldn't get across the Mississippi River to the East where they were so desperately needed.

Let me suggest, as an alternative to Glorieta Pass, the Battle of Chattanooga (I'm from Chattanooga, but I firmly deny any bias - that's my story and I'm sticking to it). Confederate general Braxton had soundly defeated the Union Army of the Cumberland, under Maj. Gen. William Rosecrans, at Chickamauga, and now had them besieged in Chattanooga. Had not Ulysses Grant replaced Rosecrans, lifted the siege, and then driven Bragg away from the heights around the city, the Army of the Cumberland might have been captured or destroyed. That force went on to be the nucleus of the army Sherman led on his march to the sea. So, its loss at Chattanooga would have changed the entire course of the war.

Finally, it was Grant's victory at Chattanooga that launched him into his role as Lt. General and commander of the entire Union army, and the one man (second to Lincoln) most responsible for the final defeat of the Confederacy.

CJ Kelly from the PNW on September 07, 2017:

Great job. I had very little knowledge of Glorieta Pass and the Civil War in the west in general, so I learned a lot.

I'd give honorable mention to the Battle of Mobile Bay (it helped Lincoln tremendously) and Fort Donelson, which helped make Tennessee a launching pad for further attacks south.

Keep up the good work.