Something nobody has mentioned yet, but while we discuss the pros and cons of the Gaesetae, note that the +2 adjacency bonus for every adjacent unit, enemy or allied, applies to all Gaullic melee, anti-cav, and ranged units. As I found out this morning, that means when you do get your Gaesetae promoted to Musketmen, they go from being barely average Medieval Units to Killer Rabbits of the Renaissance. A Gaullic musketman with an enemy in front, a unit on either side and a crossbowman of two behind him attacks at +10. I took a Free City that had been Free for over 70 turns (AI Germany built his 3rd or 4th city a third of a continent away from the rest of his Civ, so of course it flipped as soon as he hit a Dark Age, and nobody was exerting any pressure on it, so it stayed Independent for the entire Classical Era, churning out units). Once they got adjacent to the city, three Musket-carrying Torc-wearing Gauls took it in one turn, with support from two crossbowmen - and the city had Ancient Walls, but 2 crossbows and one Musket attack was enough to suppress them completely.
So, playing Gaul you are going to be playing in a distinctive Cycle: Ancient and early Classical Gauls will play Barbarian Reaper and be very dangerous to 'ordinary' enemy armies: DO NOT try to fight Gaesetae with Spearmen, because you are severely penalized by the Gaesetae's and the Gaullic bonuses: even a small force of Gauls will be coming at you with Gaesetae at +40 strength. Other losses being equal, they will one-shot a Spearman - even Hoplites can't stand up to them for more than a single turn.
Then the Furor Gallicus goes dormant for the late Classical (Swordsmen) and Medieval Eras. I played nice like you wouldn't believe in my continuation game today: established Embassies, made trades, carefully did not settle next to anyone and generally Gladhanded in all directions.
Until I got Niter and Gunpowder, and now it's back to No More Mister Nice Gaul.
- or maybe not. While the Gauls have the capability to Romp and Stomp in the Renaissance and later (the adjacency stays constant at +2 per adjacent unit, though, so relatively the Bonus gets weaker vis-a-vis the basic unit strengths: It's a Killer in the early game, only a Maimer later, and probably just a Slap in the Civ Face by the late game, but never completely insignificant) having built up a Cultural and or Diplomatic/Religious 'base' while being Pacifistic for an Era and a half, by the Renaissance they can be set up to go in almost any direction they want: Oppidum-based Production leading to building Spaceship parts, Cultural from both the usual suspects and their Unit building, or religious if the requisite Districts and buildings have been built during the Era of Peace, Joy and Roast Boar Dinner Parties.
Overall, Gaesetae included, Gaul is a very flexible Civ and very interesting to play - once you understand that its characteristics require a certain finesse to get past the Late Classical/Medieval Interim Eras, it has bonuses that can usefully be applied to Domination, Cultural, or Scientific victories almost equally well.
