Thanks for the feedback Soccerman

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In game, I hadn't registered I'd maxed out on 63 villagers - got quite a surprise when I viewed the post game stats. I suspect what happened was that around the 30 min mark I was eager to start BBing so I wanted to fill all 200 pop spaces quickly - with military units - before I clicked on my BBs. I'm really going to have to watch that.
Yes, I should have used the water. I guess that mentally, because I didn't have any water cards in my deck at all, I assumed that the water was "his". This was me being lazy, these days, I'm only using one deck! I think I took out the schooner card last time I reviewed it.
I'm starting to get an appreciation for Jag Prowlers. Up until recently, I would very rarely use them ingame at all. But I've rethought them. Some notes:
(1) 'They're weak against Infantry'
But, if you stealth Jag Prowlers straight into melee combat against infantry the Jag Prowlers come out on top.
(2) They don't get their upgrade until age 4, and it's 2000 gold, c.f. Arrow Knights & Eagles
This is true. However, there are 3 dam/hp upgrade cards to play in age 3. That's more than enough to be beefing up your Jag Prowlers. And, if you focus on these three upgrades they beef up your other knights too - extra bonus - whereas the upgrades for Eagles and Arrow Knights only upgrade those units.
(3) Jags are slow
This is true. However, they have other strengths. For example, they do okay against buildings and settlers. Eagles are weak in both those areas until you do the upgrades to make up for those weaknesses. And, that's two card that could have been used on something else.
(4) Jags are spamable
They're a bit cheaper than Eagles, and, the Infantry card works on Jag Prowlers whereas it doesn't work on Eagles - for faster production.
(5) Jag/Arrow Knight Combo
Like the Arrow Knight/Eagle combo an Arrow Knight/Jag combo works well. The Arrow Knights can provoke and provide long range cover fire, and the Jags can stealth onto anything that comes near with a beefy attack.