1) Create a fleet of ships (there should be no other fleets). Be sure the fleet is selected so the box in the bottom left is visible.
2) Let the fleet lose all its ship in battle (this keeps happening to me because despite me changing my patrol preferences to "nearby targets only", I guess they drop out of patrol when they run out of fuel. Regardless, the idiot escorts go creature hunting and die.
3) The fleet box at the bottom left of the screen is visible and there are no ships in it.
4) Now hit the left (or right) "next fleet" button. You'll see the screen below:
