1779, Penobscot. The Americans turn up with far more ships and far more men than the British have, and lose anyway.
What gets them is that nobody is properly in charge. The navy wants the army to go first, the army wants the navy to go first, and every meeting ends with the attack pushed back another day while the British finish building the fort they were meant to be attacking.
It is built from real people and real timings, and it reads like watching a project go wrong in slow motion. I have been in group things that failed the same way, on a much smaller scale.