If you go to Coalition Capital, you see the flag status in the top right hand corner. Select it. To the right of Rescue Your Flag, you see Dispatch Scouts, Attack and Message icons.

If you hover over Message, the text says "You can ask other coalitions to return your flag voluntarily. If they accept, you will rescue your flag without needing to attack them."

This is the option I am referring to. In the last CTF event, we had our flag returned once by asking for it, but since then, the hegemon's can't seem to find the button that allows them to return it.