Eagle of Rome

Somehow, I gained a unit called the Eagle of Rome. My notes don't indicate what type it is. But, I noted 'to Corinth'. and 'Where?' when I was playing last week.

What is this unit? How did I gain it? Where can I reequip it(probably intention of my indecipherable notes from last week)?

When you kill off 100% of one of romes eagle units, The ones that have the eagles.
You get this eagle it goes to one of your citys, it makes the romans useually mad. It probably raises public order?