Blood slaves?

[Executor]

I had a misfortune to be attacked while bloodhunting, my mages were set to retreat, so when the battle started they retreated but the slaves stayed, I won the battle but now I have the blood slaves as regular units, not as... well not as gems,
and since they caught a large amount of bloodslaves, which is very important me not being a blood nation, is there any any way to make them usable again?