Civilization V: The Celtic Chronicle, part 1 (4000 B.C. to 1150 B.C.)

T.J. Hafer at

Warriors of song and legend

3450 B.C.: The Celts win a major victory against barbarians at what will come to be known as First Blood Bay, just east of the River Celtica. Their scavenged ranged weaponry allows them to weaken their foes from the safety of a nearby hilltop before their melee warriors move in.

3350 B.C.: Celtic warriors come across a group of explorers from the neighboring Germanic tribes being attacked by barbarians. The Celts sweep in with clubs and arrows to save the day, leaving the Germans very grateful.
I haven't spotted a German city yet, but the fact that I'm encountering them so early means they're probably pretty close by. Waging two wars in the early game is a bad idea, and I already have my eyes set on England. So I think I'll try to stay on good terms with them for now.

That same year, the establishment of a formal Warrior Code leads to the rise of a Great General in Edinburgh.
Another reason I went down the Honor tree: Having a Great General this early in the game is a pretty huge deal. This will let me take on much larger forces with only a few units of troops.