What is the title of the old war movie in which allied soldiers were landed behind enemy lines from the air in parachutes they then reassembled but were eventually trapped in a basement and flushed?

The movie you're referring to is likely "The Dirty Dozen" (1967). In this film, a group of Allied soldiers is sent on a dangerous mission behind enemy lines during World War II. While they do face numerous challenges, including being trapped and outnumbered, the specific scene of being flushed out from a basement does not directly occur in this film. It's possible you might be mixing elements from various war films.