Battle of Pharsalus
In 48 BC at the Battle of Pharsalus, Julius Caesar faced the army of Pompey, which not only outnumbered his more than four to one, but was also in more or less friendly territory. Conversely, Caesar's own army, due to his blocked crossing of the Adriatic Sea, had been cut in half as well as cut off from their supply lines. The rest of the army lay on the opposing shores of the Adriatic, unable to aid their comrades.