William Henry Harrison was the ninth U.S. president and, at 68, was the oldest to be inaugurated until Ronald Reagan in 1981 was sworn in at the age of 69. Harrison was the first president to die in office -- only 31 days after his inauguration.
 

As an Army officer and governor of the territory that is now Indiana and Illinois, he fought Indians and made harsh treaties with them, clearing the way for more westward settlement by whites. His military victories against Indians made him a hero to white Americans.
 

Harrison's father, Benjamin Harrison, signed the Declaration of Independence. William Henry Harrison's grandson, also named Benjamin Harrison, became the 23rd president.
 

Harrison's Military Career
 

William Henry Harrison studied medicine in Richmond and Philadelphia before dropping it in favor of a military career. (He is the only president who studied to become a doctor.) In 1791 he joined the Army, and through family connections obtained an officer's commission as ensign in the First Infantry. He was then 18 and in charge of about 80 men whom he had recruited to fight Indians on the Western frontier. How long did Harrison stay in the Army? 
 

Harrison stayed in the Army until 1798, leaving with the rank of captain. He was posted to Fort Washington, near Cincinnati, Ohio, and served as aide-de-camp to General "Mad Anthony" Wayne. Wayne cited him for bravery at the Battle of Fallen Timbers in 1794, an attack on Fort Washington that the U.S. Army won. This opened much of the Ohio region to white settlement. Harrison was named commander of forces at Fort Washington when General Wayne died in 1795. Did Harrison's military career end in 1798?
 

Appointed governor of the new Indiana Territory in 1800, Harrison had the job of defending and extending white settlements, and he did so by going back into battle. In 1811, as the threat organized by the Shawnee Indian chieftain Tecumseh grew stronger, Harrison successfully led about a thousand men against a Shawnee uprising on the Tippecanoe River on Nov. 7. He earned the nickname "Old Tip," but more importantly the rank of brigadier general and was given command of U.S. forces in the Northwest.
 

In 1813, during the War of 1812, Harrison defeated a joint force of British and Indian fighters at the Battle of the Thames River, near Ontario, Canada. Tecumseh was killed, and the victory ended the Indian resistance in the Northwest for good. Harrison resigned from the Army in 1814 at the age of 41.