Sherman was named Tecumseh after the famous chief of the Shawnee tribe against whom his grandfather had fought while serving under General (and later President) William Henry Harrison at the Battle of Tippecanoe. His father, Judge Charles R. Sherman, died when he was 9 years old. Following this tragedy, Sherman was taken in and raised by a family friend, attorney Thomas Ewing, a prominent member of the Whig Party who served as a Senator from Ohio and as U.S. Secretary of the Interior. The name of William was bestowed upon him at this time when Ewing's wife, Maria, insisted Sherman be baptized Roman Catholic. He never truly accepted "William", however, and friends and family always called him "Cump".
Ewing secured the appointment of Sherman at West Point, graduated in 1840. He ranked 6 out of 42 in his class. He was commissioned as a second lieutenant in the 3rd U.S. Artillery and saw action in Florida in the fight against the Seminole tribe. During the Mexican War, he performed administrative duties while stationed in California and received a brevet promotion to captain.
In 1850, Sherman married Thomas Ewing's daughter, Eleanor B. Ewing. Three years later, he resigned his military commission and became president of a bank in San Francisco. He survived 2 shipwrecks and floated through the Golden Gate on the scraps of a lumber schooner. He eventually found himself suffering from stress-related asthma. In 1856, he served as a major general of the California militia.
Sherman's bank failed during the financial panic of 1857 and he became a lawyer in Leavenworth, Kansas, at which he was unsuccessful. In 1859, he accepted a job as the superintendent of the Louisiana State Seminary of Learning and Military Academy, later becaming Louisiana State University.
In January 1861, just before the outbreak of the Civil War, Sherman was required to accept receipt of arms surrendered by the U.S. Arsenal at Baton Rouge. He resigned his position and returned to the North, declaring to the governor of Louisiana, "On no earthly account will I do any act or think any thought hostile ... to the ... United States." He became president of the St. Louis Railroad, a streetcar company, a position he held for only a few months before being called to Washington, D.C.
Sherman accepted a commission as a Colonel in the 13th U.S. Infantry regiment on May 14, 1861. He was one of the few Union officers to distinguish themselves at the First Battle of Bull Run, where he was grazed by bullets in the knee and shoulder. The Union defeat led Sherman to question his own judgment as an officer and to request that President Abraham Lincoln relieve him of independent command, which Lincoln refused to do, promoting him instead to Brigadier General. He was assigned to command the Department of the Cumberland in Louisville, Kentucky.
While in Louisville, Sherman went through a personal crisis. At a time when he was probably working too hard, as well as drinking and smoking too much, he suffered from a personal collapse that made it necessary for him to go home to Ohio to recuperate. He quickly returned to service under Gen. Henry W. Halleck and just 6 months later, he fought as a division commander under Major Gen. Ulysses S. Grant at the Battle of Shiloh. Despite bearing the brunt of the initial surprise Confederate attack, he rallied his division and prevented a disastrous defeat. He was wounded in the hand and had 4 horses shot from under him. He was promoted to major general of volunteers after the battle.
Sherman developed close personal ties to Grant during the two years they served together. At one point, not long after Shiloh, Sherman persuaded Grant not to resign from the army, despite the serious difficulties he was having with Halleck, his commander. In later years, Sherman said simply, "Grant stood by me when I was crazy, and I stood by him when he was drunk. Now we stand by each other always."
When Lincoln called Grant east in the spring of 1864 to take command of all Union armies, Grant appointed Sherman his successor as commander of the Western Theater of the war. Sherman's siege and capture of Atlanta and the subsequent "March to the Sea" Campaign made a great contribution to Abraham Lincoln's re-election as president and the successful conclusion of the war. He captured Savannah on December 21. On December 25, he telegraphed to Lincoln, "I beg to present you as a Christmas gift, the city of Savannah with 150 heavy guns and plenty of ammunition, and also about 25,000 bales of cotton." In the spring of 1865, his army proceeded north through South Carolina, burning the state capital of Columbia, and he accepted the surrender of Gen. Joseph E. Johnston's army in North Carolina.
Sherman was convinced that the Confederacy's ability to wage further war had to be crushed if the war was to end. Therefore, he believed that the North had to employ scorched earth tactics to destroy the economic and military backbone of the South. His advance through Georgia and the Carolinas was characterized by widespread destruction of civilian supplies and infrastructure. This was the point—to destroy the will and ability of the South to make war.
Accusations that civilians were targeted and war crimes were committed on the march have made Sherman a controversial figure to this day, particularly in the South. The damage done by Sherman was almost entirely limited to property destruction—particularly property that could aid the Confederate war effort. He was more than a little duplicitous when it came to his views and treatment of blacks. He disapproved of chattel slavery and his actions freed many slaves, but he, like many of his time, was not a believer in "Negro equality".
In 1866, Sherman was promoted to lieutenant general and when Grant became president in 1869, he was promoted to full general and served as Commander-in-Chief of the U.S. Army until his retirement in 1884. For one month in 1869, he served as the interim Secretary of War. In 1871-72, on leave of absence, made a tour of Europe and the Far East. One of his significant contributions as head of the Army was the establishment of the Command School (now the Command and General Staff College) at Fort Leavenworth.
In Sherman's various campaigns against the Indian tribes, he repeated his Civil War strategy by seeking not only to defeat the enemy's soldiers, but also to destroy the resources that allowed them to sustain its warfare. Despite his harsh treatment of the warring Indian tribes, he spoke out against government agents who treated the natives unfairly within the reservations.
In 1875, Sherman published his 2-volume memoirs.
After retiring from the army in 1884, Sherman lived most of the rest of his life in New York City. He was in demand as a colorful speaker at dinners and banquets. He was proposed by some Democrats as a possible presidential candidate for the 1884 presidential election, but declined, saying, "If nominated I will not run; if elected I will not serve."