There are testimonies about these events such as the Solomon bar Simson Chronicle, the Eliezer ben Nathan Chronicle, Mainz Anonymous Chronicle.
During the Rhineland massacres (1096) and the Worms massacre (1096) thousands of Jews were martyred notable amongst them was Kalonymus ben Meshullam and his sons (died 1096) and Minna of Worms (died 1096).

A special Hebrew prayer, Av HaRachamim ("Father [of] Mercy") still recited in Ashkenazi synagogues today was composed commemorating the Jewish martyrs resulting from the First Crusade (1096-1099).

The Rintfleisch massacres (1298) notably Mordechai ben Hillel (1250-1298).
Erfurt massacre (1349) notably Alexander Suslin (died 1349).
There are testimonies about these events such as the Solomon bar Simson Chronicle, the Eliezer ben Nathan Chronicle, Mainz Anonymous Chronicle. During the Rhineland massacres (1096) and the Worms massacre (1096) thousands of Jews were martyred notable amongst them was Kalonymus ben Meshullam and his sons (died 1096) and Minna of Worms (died 1096). 
A special Hebrew prayer, Av HaRachamim ("Father [of] Mercy") still recited in Ashkenazi synagogues today was composed commemorating the Jewish martyrs resulting from the First Crusade (1096-1099).
The Rintfleisch massacres (1298) notably Mordechai ben Hillel (1250-1298). Erfurt massacre (1349) notably Alexander Suslin (died 1349).
Martyrdom in Judaism