Following high school, William Jr. received a senatorial appointment from Texas to the United States Military Academy at West Point, New York in May 1913.

Other classmates include: Clare H. Armstrong, Aaron Bradshaw Jr., Mark W. Clark, John T. Cole, Norman Cota, John M. Devine, William W. Eagles, Theodore Leslie Futch, Charles H. Gerhardt, Augustus M. Gurney, Ernest N. Harmon, Arthur M. Harper, Robert W. Hasbrouck, Frederick Augustus Irving, Laurence B. Keiser, Charles S. Kilburn, Bryant E. Moore, Daniel Noce, Onslow S. Rolfe, Herbert N. Schwarzkopf, Albert C. Smith, George D. Wahl, Raymond E. S. Williamson, and George H.

[6][3] Harrison graduated with a Bachelor of Science degree on April 20, 1917, shortly following the United States entry into World War I, and was commissioned a second lieutenant in the cavalry branch.

Harrison reached consecutively the ranks of first lieutenant and captain and returned to West Point Military Academy as an instructor of French and Spanish languages.

[6] Harrison was later transferred to the 7th Cavalry Regiment at Fort Bliss, Texas and served with that unit until early 1923, when he was ordered to Washington, D.C. for duty on the staff of the Army War College.

[6][4] Following the American entry into World War II, Harrison was promoted to the temporary rank of colonel on December 11, 1941, just four days after the Japanese attack on Pearl Harbor.

[1][6][2][4] Harrison was replaced by Brigadier General John K. Rice and appointed ADC under Hobbs, who tasked him with organization of the 30th Infantry Division's training at Camp Blanding, Florida.

Harrison participated in the combat at Vire-et-Taute Canal and on Vire River and quickly won the admiration of his troops by accompanying them on the front lines with M3 submachine gun in hand.

Harrison escaped from the damaged vehicle and hit the ditch, where he immediately dispatched his aide and driver to contact the next ranking officer in order that he might continue the advance.

He did not mention his wounds, which were not visible due to his raincoat and crawled approximately 600 yards to the rear of the column in order to give further instructions for continuing the mission.

The 30th Division then proceeded to the Netherlands, where they liberated the town of Kerkrade on September 25, 1944, and advanced to Germany, where they took part in the combat on the Siegfried Line and subsequently in the battle of the heavily defended city of Aachen on October 2.

[4] The 30th Infantry Division was ordered for rest and refit to the rear by the end of November 1944 and transferred to the Ninth United States Army under Lieutenant General William H. Simpson.

Harrison was tasked by Simpson himself to conduct a refresher course for all infantry and artillery commanders in the Ninth United States Army, down to the battalion level.

Harrison lectured the tactics employed by his command in the taking of several towns and then took the entire class to the field to Sankt Jöris near Aachen, where artillery and tanks were set up to demonstrate how they had been used in the attack there.

[4] Harrison and 30th Division returned to the front lines following the launch of the massive German offensive in the Ardennes on December 17, 1944, and participated in combat in the Malmedy-Stavelot area.

After taking Hamelin and Braunschweig at the beginning of April 1945, the 30th Division Task Force under Harrison's command discovered two large groups of Hungarian Jewish women at Teutoburg Forest.

[4] On April 13, 1945, Harrison participated in the efforts to save 2,400 prisoners from the Neuengamme concentration camp subcamp at Farsleben, whom they found locked in train boxcars.

[7][6][4][5] Harrison then participated in the occupation duty in Germany in Magdeburg until June 1945, when he was appointed the acting commanding general of the 2nd Infantry Division located between Prague and Pilsen, Czechoslovakia.

Harrison was then appointed commanding general at Camp Carson, Colorado, where he was responsible for the demobilization of troops returning from war zones in Europe and Pacific.

[1][4] Harrison was promoted again to brigadier general on January 24, 1948, and appointed Chief of the Reparations Section at the headquarters of the Supreme Commander for the Allied Powers and held this assignment until December 1948, when he was ordered back to the United States.

[1][4] He was subsequently appointed Chief of the Armed Forces Information and Education Division of the Department of the Army in Washington, D.C. and was promoted to major general on March 11, 1949.

He didn't like that job and following the outbreak of the Korean War, he applied to be assigned to a field command, hoping that the Army Chief of Personnel, Matthew B. Ridgway, who was his friend and West Point classmate, would help him.

During sixteen-week training cycles, he had to transform young men into effective soldiers, but his methods were not met with understanding by some of the recruits' parents and also with some unfavorable press.

When the father of one recruit was invited to spend a week at the barracks with his son, he changed his mind and upon returning home, he wrote a second letter to the editor of the newspaper, withdrawing all his criticism.

[4][5] Harrison was finally ordered to South Korea in December 1951 and appointed deputy commander of the Eighth United States Army under General James Van Fleet, whom he respected as a combat troop leader.

[1][6][4] Harrison was attached to the U.S. team under Vice Admiral C. Turner Joy and participated in the regular negotiations with North Korean and Chinese representatives at Panmunjon.

He despised the communists, who he regarded with contempt as common criminals and for example in June 1952, he left the truce meeting, when he saw that the negotiation was without result, leaving North Korean General Nam Il flabbergasted.

He then arrived at the Panama Canal Zone on June 16, 1954, and assumed duties as the commander-in-chief of the United States Caribbean Command with headquarters in Quarry Heights.

Harrison participated in many ceremonies including the Inauguration of President Ernesto de la Guardia in October 1956 (as a member of the United States delegation).

[1][6][8][4][13] Harrison retired from the Army on February 28, 1957, after almost 40 years of service and settled in Chicago, where he served as executive director of the Evangelical Child Welfare Agency until 1960.