News of Emicho's crusade spreads quickly, and he is prevented from entering Mainz on May 25 by Bishop Ruthard.

Emicho also takes an offering of gold raised by the Jews of Mainz in hope to gain his favor and their safety.

Bishop Ruthard tries to protect the Jews by hiding them in his lightly fortified palace.

Nevertheless Emicho does not prevent his followers from entering the city on May 27 and a massacre follows.

Many among the Christian business class (the burghers) in Mainz, have working ties with Jews and give them shelter from the mobs (as the burghers in Prague also do).

The Mainz burghers join with the militia of the bishop and the burgrave (the town's military governor) in fighting off the first waves of crusaders.

This stand has to be abandoned when crusaders continue to arrive in ever greater numbers,and the militia of the bishop together with the bishop himself flees and leaves the Jews to be slaughtered by the crusaders Despite the example of the burghers, many ordinary citizens in Mainz and other the towns are caught up in the frenzy and joined in the persecution and pillaging.

Mainz is the site of the greatest violence, with at least eleven hundred Jews and (possibly more) being killed by troops under Clarambaud and Thomas.

The idea of suicide, normally abhorrent, is considered acceptable or even preferable under these circumstances.

One man, named Isaac, is forcefully converted, together with his two daughters and a friend called Uriah, but later, wracked with guilt, kills his family and burns himself alive in his house.

Another woman, Rachel, kills her four children with her own hands so that they will not be cruelly killed by the crusaders.