Joseph Hooker was born on November 13, 1814 in Hadley, Massachusetts. As a youth, he studied at the Hopkins Academy before joining the army and going to the US Military Academy. In 1837, he graduated and was made a second lieutenant in the 1st US Artillery.

He was immediately sent to Florida, where the second war against the Seminole Indian Tribe was taking place. Eventually, he was promoted to a staff position under generals Zachary Taylor and Winfield Scott during the Mexican-American War that began in 1846.

The first battle he fought in during that war was the attack on Monterrey, after which he was promoted to the rank of Captain. In the Battle of National Bridge, he again served with skill and was promoted to Major. In the Battle of Chapultepec, he was again promoted, this time to the rank of Lieutenant Colonel.

Following the war, he was assigned to work as the assistant adjutant general for the Pacific Division of the US Army. When a court martial was held against his former commander, Winfield Scott, Hooker testified against him to assert that Scott had not followed the orders of his superior, Gideon Pillow. The resulting backlash led him to resign from the military in 1853.

After leaving the military, he moved to Sonoma County in California, where he started a farm. However, he did not enjoy his profession since he spent most of his time drunk and/or gambling. In 1858, he wrote a letter to John Floyd, then the Secretary of War, and requested that he be reassigned to the military. His letter was not replied to and he instead decided to become a Colonel in the local militia.

When the Civil War began, Hooker applied to be commissioned as an officer, but his application was denied. He moved to the east and managed to witness the First Battle of Bull Run, which was a disaster for the Union Army. He wrote to President Lincoln, decrying the mismanagement of the military and requesting a commission.

In August of 1861, he was appointed Brigadier General and placed in command of a division near Washington DC. His superior was George McClellan and they became part of the Army of the Potomac. In 1862, they were sent into battle, with Hooker in command of the 2nd Division of the 3rd Corps.

Hooker immediately reestablished himself as a skilled leader during the Battle of Williamsburg and the Seven Days Battles. For his achievements, he was promoted to the rank of Major General. Hooker was not pleased with the leadership of McClellan, who he criticized for being too cautious.

Eventually, Hooker was transferred to work under John Pope in the 3rd Corps of the Army of Virginia. After two major defeats of the 3rd Corps, which was then led by Samuel Heintzelman, Hooker was given command of the Corps and fought battles at South Mountain and Antietam.

During the Battle of Antietam, Hooker launched the first assault in the battle and attacked the forces led by Stonewall Jackson. Hooker was forced to leave the battlefield after receiving a wound to his foot and the battle proved to be a failure for the Union Army. Hooker later claimed that they would have won if he had not been forced to leave the field.

After Antietam, Hooker was made commander of the 3rd and 5th Corps of the Army of the Potomac. McClellan was replaced by Ambrose Burnside, who led the Army of the Potomac to besiege the city of Fredericksburg. Burnside ordered Hooker to attack the fortified walls behind the city, despite Hooker's protests, and the assault ended in many futile casualties. After the Mud March in early 1863, Hooker was so disenchanted with Burnside that he referred to him as a "wretch".

Lincoln swiftly removed Burnside after he called for a purging of leadership in the Army of the Potomac, including Hooker. Hooker was instead made commander of the Army of the Potomac and officially took the position on January 26, 1863. Hooker immediately began reorganizing the army and increasing morale after its many devastating defeats in 1862. He proudly claimed, "I have the finest army on the planet. May God have mercy on General Lee, for I will have none."

Hooker was famous among his soldiers for his hard lifestyle. The Army of the Potomac's headquarters was described as something between a bar and brothel, with women and drink constantly being present. Hooker was a notorious ladies man, but did not let it get in the way of his military command.

Hooker formulated a strategic plan to end the war within a year. He intended to send his cavalry to assault the rear of Lee's Army, which would distract him. Hooker would then advance infantry to seize Fredericksburg and flank Lee's troops at Richmond.

He initiated the plan by sending cavalry led by George Stoneman, but Stoneman did not manage to cause much disruption behind enemy lines. Hooker then advanced to flank Lee, but poorly decided to withdraw to the town of Chancellorsville to await Lee's attack. Lee sent Stonewall Jackson to flank Hooker while he made a frontal assault and they successfully routed Hooker's Army, sending them into a retreat. Hooker largely attributed the failure to his being unconscious for the day, having been struck by a wooden shrapnel from a cannonball.

The failure at Chancellorsville was Hooker's worst defeat and it gave his subordinates pause. Many called for him to hand over command to Darius Couch, but he rebuffed their attempts and led the Army of the Potomac north, where the Confederates were attacking Union territory. He was ordered to protect Washington DC at all costs and to locate Lee's forces and attack them.

Three days before the Battle of Gettysburg, Hooker got into an argument with Lincoln and General Halleck at his headquarters. He angrily offered his resignation, which was accepted, and George Meade took over command of the Army of the Potomac. Later, he was made commander of the 6th and 7th Corps of the Army of the Potomac and sent to reinforce the Army of the Cumberland.

Hooker then fought under Ulysses S. Grant at the victorious Battles of Lookout Mountain and Chattanooga. He was promoted to the rank of Major General, but was saddened when he discovered that Grant had credited Sherman for the victory at Chattanooga. In 1864, he led his troops under the command of Sherman to capture the city of Atlanta, but was relieved of his command when he protested the promotion of Oliver Howard. He spent the rest of the war watching over Michigan, Ohio, Indiana, and Illinois.

Following the war, he met a woman named Olivia Groesbeck, who was the sister of a congressman, and they were married. In 1868, he retired from the US Army at the rank of Major General due to poor health. On October 31, 1879, he died while visiting New York and was buried in Cincinnati, Ohio.