I recommend scouring your campaign map, probably some idiot country is blockading a port w/ 20 mighty warships of yours, with a puny force of 2 tugboats.

Or perhaps a mighty super city of yours, loaded w/ 12 arquebusiers, 4 spear militias, and 4 heavy bill militias, is being assaulted by a force of 2 ballistae, and a militia crossbow unit...

BECAUSE THE AI IS THAT DUMB...