Pre-Battle CTD

[rocketman120]

The year is late 230s BC, and I am preparing to siege both the Lusotann capital, and an Aedui city. After my turn ends, I fight the Aedui, and after that battle, I'm attacked by one of Lusotann's armies. However, everytime I press 'Fight Battle', the game begins to load, before I receive a CTD halfway through the loading process. This has happened before, so I ended up auto-resolving the battle that time. I have also made multiple saves, but something like this happens every once in a while, and auto-resolving typically gives me a horrible defeat. The uploaded save file is here:

http://uploaded.to/file/sjwb8y

Any help is appreciated.