Before the battle
ISIS had been rapidly expanding, more than doubling its size in just 2 days, gaining lots of support aswell as becoming more hostile, about an hour after the llamaists declared a crusade on ISIS to assist the christians already crusading, they gathered support as they moved south, originally to Raqqa they later went to mosul after seeing goober_bang on the dynamap there,
Once arriving the crusaders and the byzantine supporter surrounded mosul, for about 3 minutes little happened, afterwards though ISIS began making traps for them and pouring down lava, during this time armenians began to come and support the siege. At this point the battle began to escalate as PVP begun, around mosul was fighting for about 10 minutes against ISIS, as time went on another Byzantine and about 3 more armenians came to support, about halfway through the battle it was at its peak intensity, by this point there were already 3 casualties and parts of mosul were broken by there own citizens in an attempt to trap the crusaders, but eventually more and more crusaders began to fall, although near the end of the battle one of the ISIS defenders of mosul were killed, but by this point there were no more than 3 crusaders at mosul, shortly after they surrendered.
The Siege of Mosul was one of the largest battles in the crusade so far, the largest if you do not include the battle of Raqqa. The amount of crusader casualties vs the amount of ISIS casualties were also similar to that of Raqqa but not as lopsided. out of the 12 people who fought in the battle, 9 were killed. this battle, along with the battle of Raqqa both showed that ISIS, despite being only 4 or 5 towns, is powerful enough to challenge even a superpower, but because of these 2 battles (and the Battle of Al Hasakah soon after) the soldiers who fight ISIS in the future would have to be more organized and cautious.