Episode 14, Charlemagne and Hannibal have Nobunaga on the ropes and Jeane in their clutches. Then at the urging of Ichihime, Caesar shows up with Uesugi Kenshin. Who kills Charlemagne in a matter of seconds.
The above doesn't really do things justice. First, Caesar blasts away the snowstorm dome, weakinging Hannibal and Charlemagne. Hannibal immediately orders her reserves into action - when is when Uesugi Kenshin shows up to do a Foe-Tossing Charge, and then utterly curbstomping Hannibal and Charlemagne.
Pretty much everything Alexander does on screen in Episode 18.