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On turn 7 I issued a 50% "attack only" followed by a 100% "attack/transfer" from the same territory. The first order didn't execute because I've already occupied the target at that point, but I don't understand why the second order also failed to execute (I expected to attack with 6). Can anyone enlighten me?

Hmm.. it looks like you found a bug!

When your first 50% attack-only order failed, it should have seen that there were 12 available armies, multiplied it by the 50%, and marked 6 of them as "used" armies that can't participate in further attacks that turn.

Instead, it skipped the multiply step and incorrectly marked all of the armies as used instead of just 6.

This will be fixed in the next release, which should hopefully be this weekend. Thanks for reporting it!

It's hardly surprising Warlight's been around for four years when the game's creator responds to a bug report in 20 minutes :) Cheers Fizzer!