[35]
Truman was brought up in the Presbyterian and Baptist churches,[53] but avoided revivals and sometimes ridiculed revivalist preachers.[54] He rarely spoke about religion, which to him, primarily meant ethical behavior along traditional Protestant lines.[55] Truman once wrote in a letter to his future wife, Bess: "You know that I know nothing about Lent and such things..."[56] Most of the soldiers he commanded in the war were Catholics, and one of his close friends was the 129th Field Artillery's chaplain, Monsignor L. Curtis Tiernan.[57] The two remained friends until Tiernan's death in 1960.[58] Developing leadership and interpersonal skills that later made him a successful politician helped Truman get along with his Catholic soldiers, as he did with soldiers of other Christian denominations and the unit's Jewish members.[59][60]

Officers' Reserve Corps
Officers of the 129th Field Artillery, at regimental headquarters at Chateau le Chanay near Courcemont, France, March 1919. Captain Harry S. Truman is pictured in the second row, third from the right.
Truman was honorably discharged from the Army as a captain on May 6, 1919.[61] In 1920, he was appointed a major in the Officers Reserve Corps.