The AI appears to have issues with using a reinforcement army in battle in 2.03c.
The situation: I'm Pontos, at war with Hayasdan. Have smashed multiple Hai full stacks, thanks to the excellent Pontic FM cavalry. Nevertheless, the war goes poorly, because Hayasdan is pumping out full stack after full stack as if it's Arche Seleukeia, while I can barely maintain one full stack.
My army is attacked by two adjacent Hai stacks; the smaller one (~650 men) is the attacker, while the larger one (~2100 men) is the reinforcements. I array my army on high ground, absorb the initial blow from the smaller army alone, rout it.
The reinforcement army sat there and did nothing useful... the AI shuffled around troops, building a big conga line of cavalry and light troops, occasionally moving the line forward and adding a new unit to the back. Most of its infantry was in a row formation behind the horse column.
I eventually won the battle on time; my army's in kind of bad shape, so I couldn't afford the losses from attacking.
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