Some Muslims were in his army, others weren't. I am just stating the truth, I am not saying I am on Menelik's side. I am not on his side, nor am I a fan of his.
We were conquered due to 1-lack of firearms, and 2-lack of unity.
Somali's, some allied with ras makonnen, father of haile selassie, one of menelik's closest generals, so he established ''katamas'' there, or military bases, and this is what they based their claims to the ogaden/somali lands later on.
My family is mostly from Jimma, my mom's dad, and my dad's dad are Jimman, but also some from Guji, and my great grandma is full silte. so, the Jimma side, had 50 guns, and gobana came and said ''look bro, we will destroy you, you cannot resist our european firearms, so if you submit, and pay taxes yearly, we won't build churches in jimma and we will allow you self-administration,'' and jimma abba jifar agreed, because he didn't want his people to be massacred and then, have churches forcefully built there. You can disagree or agree with his move, but that's what happened bro.