February 19 0197

Lucius Septimius Severus' Arm Beats Clodius Albinus Lyon 

The Battle of Lugdunum, also called the battle of Lyon, was fought on 19 February 0197 at Lugdunum (Modern Lyon, France), between the armies of the Roman Emperor Septimius Severus and the Roman usurper Clodius Albinus. Severus' victory finally established him as the sole Emperor of the Roman Empire.
This battle is said to be the largest, most hard fought and bloodiest of all clashes between Roman forces. The historian Cassius Dio places the number involved as 300,000 or 150,000 on either side of the battle. This figure has been disputed, as this is approximately three-quarters of the total number of soldiers present throughout the Roman Empire at that time. However, it is widely accepted that the total number of soldiers and support personnel involved exceeded 100,000 and could well have come close to the 150,000 figure Dio gives. 

February 14 1076

Pope Gregory VII Excommunicates Henry IV

In the 11th century Pope Gregory VII excommunicated the Holy Roman Emperor, Henry IV. Their disagreement was about who had the right to appoint church officials. When he excommunicated Henry IV, Pope Gregory also told Henry's vassals (noblemen who rented the Emperor's lands) that they did not need to give there support to the Emperor anymore. Once the Pope had told them that they did not owe anything to Henry, the German vassals staged a revolution. Henry was forced to give in and he had to go to Pope Gregory to apologize. The Pope left Henry standing for three days in the snow before he would see him. When things returned to normal, however, Henry went to rome and he threw the Pope out. Gregory was forced into exile, and he died in Salerno in 1085.