All right something is wrong here -- 2nd time! I loaded a savegame obviously and started a few turns back. This time he died in the last minutes of a very decisive fort siege battle. I had Alexander close to the action, but behind my main line, so not even fighting.
After demolishing 2 of their towers, the Thracians sallied out. They did a surprising amount of damage to the silver shields (these do not perform well, but this is for another time), but as you can see from this screenshot as proof, overall I took very few casualties compared to the Thracians 2000+ .... but I looked away for 30 seconds as their last few units were making their stand and he was dead. There were a about 3 doryphoroi hanging on along with a triballi infantry unit and 2-3 ranged units. Their general was routing already. I assume some javelins/arrows were shot over my main line into Alexander's bodyguard but I didn't even see, so not sure, it happened so fast. Only 70 of them left
This is getting insane... weakest general unit I've ever seen in DeI! They must be butter against missiles?