Go Republic Rangers!
130 A.D.: The French and the Swedes make peace.
Growing resentful of how fast their territory, religion, and influence is spreading, Russia and Germany issue public denouncements of the Celts.
Uh oh. There go my two longest-standing allies. This tends to happen if you're doing a little too well in Civ. Certain leaders get intimidated, and you can find your meteoric rise countered by gravity in a quick and painful way.
Celtic archers begin using advanced Composite Bows, with the first unit to do so becoming known as the Republic Rangers.
When you reach the appropriate tech, you can spend gold to upgrade a unit to a more advanced version. I took advantage of this with my hardened, veteran archers that have been with me since they were mere scouts, discovering bows in an ancient ruin very early on. They've seen every major battle I've been a part of for the entire game so far, and were more than deserving of some new toys.
Later that year, the Swedes request Republic aid in a renewed war on Germany. Hoping to foster peace once the pretenders of the so-called English monarchy are dealt with, the Celts respectfully decline.
It's very tempting to go to war with one of the civs that just denounced me on very shaky grounds, but my vision of a peaceful future for the Celtic Republic causes me to hold back. Besides, I don't want to give Germany even more reasons to dislike me.
160 A.D.: With London surrounded, England begs for peace, having no ransom left to pay. The Celts insist that there can be no peace as long as PC-rejecting infidels claim rightful rule over the good, English subjects of the Republic.
Word arrives from across the sea that a new religion has been founded in a faraway land.
So, my first competition. You can't rename other people's religions, but for the sake of thematic narrative, I've nicknamed the new faith of Christianity "Nintendoism," and will continue to refer to it as such for the rest of the game. We can pretend that cross is a D-pad.