Filmed with the full cooperation of the U.S. Army, Breakthrough is a lean, no-nonsense war film set during the 1944 invasion of the continent. Led by Captain Hale (David Brian), a small group of infantrymen march through Normandy. The war-weary foot soldiers resent the presence of 90 Day Wonder lieutenant Joe Mallory (John Agar), but before long he proves his value to the platoon. The supporting characters are the usual aggregation of "types," though for the most part the usual cliches are avoided (so far as can be determined, nobody mentions the Brooklyn Dodgers). The only woman in the cast is Suzanne Dalbert, playing a Normandy villager with whom the GIs briefly dally. Near the beginning of Breakthrough, several scenes of actual combat training are deftly inserted into the dramatized sequences.
by Hal Erickson synopsis