A brief overview of the main achievements in the field of applied acoustics that served the needs of defense during the Great Patriotic War and their subsequent development is given. The review is divided into three parts: (1) underwater sound, (2) air acoustics and (3) applications to medicine. Each section provides historical information about the most important developments during the war, as well as their development after the Victory. Physical phenomena underlying technical solutions are indicated, and acoustic specificity is emphasized.