There could be a theme of justice. If it's an operation like a police operation to catch criminals, then justice would be at the heart of it. It could also be about discovery. Maybe it was an archaeological operation where they were trying to discover something important. The true - story aspect means these themes would be grounded in real - life experiences and emotions, making them more impactful.
One possible theme could be sacrifice. If it's a true - story - based operation, there were likely people who had to give up something for the greater good within that operation. Another theme might be perseverance. They had to keep going in the face of difficulties.