That depends on the level of your Himeji Castle. At level 1 it's a 7% chance the first 4 successfull battles. Both the chance and number of battles then increase with the levels
as you can see here: https://forgeofempires.fandom.com/wiki/Himeji_Castle
You can win the spoils as many time as many "tries" you have.
So if you have a chance to activate the spoils of war in your first X battles, you can win the spoils of war up to X times. That is rather unlikely though, especially on the lower levels - but I already had it happen that I got at least 7 of the 9 possible spoils of war from my Level 58 HC.
Thanks for your feedback, very helpful. A follow up to this...can a player win spoils from winning war during GE battles? I only have a L6 and L7 HC, but haven’t won once in GE. Just bad luck?
You can get the spoils from any won battle no matter where... so probably just bad luck...
I have a level 65 HC. I have won spoils of war from every kind of battle available.. At your still low level HC it's probably just bad luck. But if I would use all my 9 tries with 47 % chance each time on GE battles and get no spoils of war at all it would be a bit strange.
What do you think?