Complex sentence: He served as operations officer for the 34th Bombardment Group at Geiger Field, Spokane, Washington., and in December 1942 he was assigned as deputy commander of the 88th Bombardment Group at Walla Walla, Washington where he later became commander.
Split into simpler sentences: He served as operations officer for the 34th Bombardment Group at Geiger Field, Spokane, Washington. In December 1942, he was assigned as deputy commander of the 88th Bombardment Group at Walla Walla, Washington, where he later became commander.