The Deadliest Battles in American History

The United States was established on the back of a deadly war. The Revolutionary War, also known as the War of Independence, saw the Continental colonies at war with Great Britain and resulted in the deaths of thousands of patriots. Since then, the nation has been involved in several destructive conflicts and has not always emerged triumphant. The deadliest battles in American history took place across more than a century and on several continents.

War is an unfortunate reality, and even harsher still is U.S. military has not had a decisive victory in a major war since the Second World War. The Korean War had no clear-cut winner and ended with an armistice agreement, although no side was satisfied. Vietnam ended in defeat, with control of the country going back to North Vietnam which reunified the country under communism. Assessing U.S. engagements in Afghanistan and Iraq yields ambiguous results, with no clear-cut victories.

To compile a list of the deadliest battles in American history, 24/7 Tempo referenced various military, historical, and general interest websites. Our selections were based on the severity of the disaster and its impact on the course of the war. In certain instances, despite achieving victory, the U.S. (or the Union Army during the Civil War) faced substantial losses during the conflict.

It is important to note that casualties don't exclusively refer to deaths. In military terminology, casualties include those who are killed, wounded (regardless of their eventual fate), captured, or reported missing. Military disasters often stem from two primary causes: Inadequate preparation before a battle and errors made by military commanders during the engagement. This list includes both. (Here are the most famous battles in world history.)

Here are the deadliest battles in American history:

• Date(s): August-November, 1776
• Conflict: Revolutionary War

After a series of engagements ranging from Long Island to Staten Island to the New Jersey Palisades, George Washington lost virtually all of New York City and the surrounding area to the British as his poorly prepared soldiers were overrun. On November 16 alone, some 2,800 members of the Continental Army were killed, wounded, or captured at the siege of Fort Washington.

• Date(s): Sept. 11, 1777
• Conflict: Revolutionary War

Washington was determined to prevent the British from capturing Philadelphia, then the capital of the new American nation. This was the largest battle of the Revolutionary War, involving a total of 30,000 troops, and the British under General William Howe defeated the upstart American army, successfully occupying Philadelphia despite Washington's efforts.

• Date(s): Aug. 24, 1814
• Conflict: The War of 1812

The British attacked the American militia at Bladensburg, Maryland, just northeast of Washington D.C., which had by then become the U.S. capital. The militia quickly gave way. A retreat was ordered, and the troops were seen running through the streets of Washington, joined by fleeing members of the government. The British took the city and burned the White House and other buildings, humiliating the Americans.

• Date(s): July 21, 1861
• Conflict: Civil War

The first major battle of the Civil War was a major win for the Confederates. Their victory, in the early days of the war, undermined the idea that the Union's military superiority would end the conflict quickly.

• Date(s): April 7, 1862
• Conflict: Civil War

One of the few major mistakes made by Ulysses Grant during the Civil War was his overconfidence before the Battle of Shiloh. Grant did not put up proper defenses and Confederate soldiers overran the Union camps. Grant eventually turned the tide of the battle, but casualties were horrible, with the Union side losing as many as 23,000 men.

• Date(s): July 1-3, 1863
• Conflict: Civil War

Fought as Robert E. Lee invaded Pennsylvania, the Battle of Gettysburg took a heavy toll on both sides, especially after Lee made the huge mistake of charging Union lines across a field nearly one mile across on July 3. Known as "Pickett's Charge," this sortie ended the battle, with almost 7,000 men on both sides either killed or wounded.

While the battle was a major defeat for the Confederates, costing them more than a third of their army, Union casualties were heavy, too, numbering about 23,000 over the three days the battle raged.

• Date(s): Sept. 18-20, 1863
• Conflict: Civil War

After several major losses, the Confederate Army of Tennessee broke through Union lines and forced its soldiers to retreat to Chattanooga. However, the battle may have been a bad miscalculation, as the Confederates suffered more than 18,000 casualties, a number they could ill afford.

• Date(s): June 25-26, 1876
• Conflict: Great Sioux War of 1876

By 1876, American troops had pushed Native Americans off a great majority of their land. Civil War hero George Armstrong Custer, with about 200 men, was scouting for enemy positions. Rather than wait for reinforcements as he moved into hostile areas, he moved ahead on his own. The American military had underestimated the battle prowess of the tribes, however, and he and his entire command were slaughtered.

• Date(s): Dec. 7, 1941
• Conflict: World War II

There may be no better example in history of a major military force that was caught completely by surprise and then virtually destroyed. The American military disregarded all signs that war with Japan was impending and lost virtually its entire Pacific fleet.

• Date(s): Dec. 8, 1941-May 8, 1942
• Conflict: World War II

The day after Pearl Harbor, the Japanese launched an invasion of the Philippines, then a U.S. overseas territory. American forces outnumbered the invaders, but they were mostly inexperienced recruits who had never been battle-tested and they were quickly overrun. The war between the two sides raged on for months.

By the time it ended, some 23,000 Americans and about 100,000 of their Filipino allies had been killed, wounded, or captured. Captured soldiers were forced into slave labor by the Japanese and many more died. The battle was once described as the worst military defeat in U.S. history.

• Date(s): Feb. 19-24, 1943
• Conflict: World War II

Due to poor preparations by America's senior command in North Africa, German general Erwin Rommel made a surprise attack. American and other Allied forces had to retreat 50 miles to regroup. A huge quantity of American material – tanks, half-tracks, artillery, etc. – was destroyed or taken by the Germans and so many U.S. soldiers were killed, wounded, or missing that some 7,000 replacements were needed to bring forces up to strength.

• Date(s): Dec. 16, 1944-Jan. 16, 1945
• Conflict: World War II

Late in the war, with America and its allies assuming that hostilities were essentially over since Germany had almost no capacity to defend itself from invasion, German tanks led a surprise attack, resulting in almost 90,000 American casualties, including 19.000 deaths, making this the deadliest single battle fought by the U.S. during World War II.

• Date(s): Nov. 27-Dec. 13, 1950
• Conflict: Korean War

As U.S. and allied forces pressed deep into what is now North Korea as a means to end the Korean conflict, they moved close to China. The Chinese retaliated with a force that numbered well over 100,000 soldiers. The U.S. was forced into a brutal retreat that cost nearly 15,000 casualties. One American army unit, the so-called Task Force MacLean, was almost completely wiped out. The battle also helped tip the scales of the war in the direction of North Korea and China.