The splashy, star-studded This is the Army is based on the Irving Berlin Broadway musical of the same name, which in turn was a reworking of Berlin's WW1 "barracks musical" Yip Yip Yaphank. In both instances, the cast was largely comprised of genuine servicemen, many of them either recently returned from fighting or on the verge of heading off to war. The Hollywood-imposed storyline concerns Jerry Jones (George Murphy), a member of the original 1918 Yip Yip Yaphank cast. His showbiz career curtailed by a leg injury, Jerry becomes a producer during the postwar era. When the US enters WW2, Jerry gathers together several other cast members from the 1918 Berlin musical to help him stage a new all-serviceman show, titled (what else?) This is the Army. The show-within-a-show framework is able to accommodate a romantic subplot, involving Jerry's son Johnny (Ronald Reagan, later a political comrade-in-arms of George Murphy) and Eileen Dibble (Joan Leslie), the daughter of Yip Yip Yaphank alumnus Eddie Dibble (Charles Butterworth). Some of the best moments in This is the Army are from the Broadway production itself, though the lengthy Alfred Lunt-Lynn Fontanne imitation and incessant "gay" jokes may have been too smart for the room in 1943. Guest stars include boxer Joe Louis, Kate Smith (singing "God Bless America", naturally) and Irving Berlin himself, who steals the show with his plaintive rendition of "Oh, How I Hate to Get Up in the Morning". All profits for the stage and film version of This is the Army went to the Army Emergency Relief Fund, which also controlled the rights to the film. Long withheld from TV distribution, the film finally hit the small screen when it lapsed into Public Domain in the mid-1970s.
by Hal Erickson synopsis