Fustat definitely would flip, its not a question of if, its when. Jaen might be brand new, but it already has some base culture. Top it up with our 20% culture slider ...

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Cultural flip depends on our cultural pressure on Fustat, and Fustat's stationed troops. Since its recently settled, Fustat can't possibly have that many troops, so there is a high chance of it flipping. It takes two revolts in Fustat for it to flip though, so unless we see a revolt in Fustat during oldbustedjorn's turnset, chances are we wouldn't see the flip.
on the millitray front, I would suggest turning off research for while, switching back to UniSuff, and then buying all we can before switching back to PS. WW would not creep in that fast.
Units wise, I think our cannons should be enough, no need to build more, considering destroyers can do the bombardments equally well. We need more ships, more infantry.
About the Infantry lost ... its sheer bad luck --

though not that extreme (Infantry is a gunpowder unit, right? so Grenadier has some bonus against Infantry).
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