The First Crusade, which took place from 1096 to 1099, resulted in significant loss of life, though exact numbers are difficult to determine. Estimates suggest that anywhere from 100,000 to 300,000 people died during this period, including both combatants and civilians.
To break it down, many of the casualties were soldiers from various European regions who embarked on the crusade. Roughly 60,000 to 100,000 knights and foot soldiers participated, and many perished in battles against Muslim forces or due to hardships such as disease, starvation, and harsh travel conditions.
Additionally, the siege of cities like Jerusalem in 1099 saw heavy casualties on both sides. The civilian population in areas affected by the crusade also suffered greatly, although these numbers are harder to quantify. Overall, the First Crusade was marked by significant bloodshed, making it one of the bloodiest events of the Middle Ages.