I saw a movie about a group of cadets on a training space craft. Their commander (played by Gary Lockwood I think) and a blond female weapons officer are killed early on. This left the cadets to find ways to stop the enemy. They are able with a number of clever maneuvers to reduce an invasion fleet of the enemy such that it is no longer a viable force for invasion.
Can Anyone Identify this movie from more than 10 years ago and maybe 40?