War really isn't fair. On wave 54, a Panzer IV Tank arrived, wave 56, a Tiger tore up what was left, and on wave 59, a WESPE joined the party, killing most of the germans on the map, and the two previous tanks. :D Wave 60= 299 kills.
A good strategy to use is to get a bunch of monkey apprentices and give them the tornado upgrade. Have one every so often, and almost no bloons can get past them.