Crassus

Crassus may have been one of the three most powerful men in Rome during the years of transition between the Republic and the Empire, but when it came to military matters, he was a fish out of water. More of a politician than a military leader, his one main campaign was marked by incredible stupidity and total defeat, as well as Crassus' death. He ignored offers of help from other Romans, trusted dubious sources of information, did not truly understand his enemies, and was caught unprepared and lost many of his men in a single battle.