A day

"Gerard, pass my orders. During this next wave, all able soldiers will go out to attack and finish off the wave as quickly as possible. After that, everyone will retreat. The wave after that will be fought from the fort's walls."

"Any particular reason?" Gerard asked, though he immediately dispatched several messengers to convey the message.

"One complete day on this planet is around 30 hours, give or take. We have been fighting for 29 hours already, and I have a feeling that the wave that comes at one full day will be unordinary. We cannot afford to act half heartedly. Besides, the offensive formation that the elves are setting up should almost be complete as well. It's weak, but some support is still better than no support."