The civil wars following the battle of Manzikert led to Alexius Comnenus becoming the Eastern Emperor.

At the Council of Piacenza a delegation visited Pope Urban II led by the Byzantine Emperor Alexius Comnenus to raise the problems he was having fighting the Muslims in the East. Pope Urban removed the excommunication that had been placed on the Emperor by Pope Gregory and promised to help.

Peter the Hermit's army of ordinary people was large and it needed feeding. One of the more noble members of the army was Walter Sans Avoir, also known as Walter the Penniless. When the army reached Cologne in April Peter decided to halt the army to take advantage of the good supply of food. Walter was impatient and with a small section of the army continued on. They passed through Hungary but at the town of Semlin a dispute broke out when some of his men stole food. When his men were refused food at Belgrade because the harvest had not yet been gathered Walter's army began pillaging the surrounding area. Finally Alexius Comnenus sent supplies and an escort to guard the Crusaders as they marched to Constantinople. The guard ensured that the Crusaders didn't cause any more trouble.

When the crusaders arrived at Constantinople they were greeted by Emperor Alexius. The Emperor was happy for the crusaders to capture areas of the Holy Land but he wanted the land to be under his control. Alexius persuaded the Leaders of the crusaders to swear an oath of allegiance to him and to hand over the land they captured. They could however be allowed to live on and rule that land but not own it.

In late 1096, Stephen of Blois, his brother-in-law Robert Curthose, duke of Normandy, along with his cousin Robert, count of Flanders set out for the Holy Land. They reached Constantinople in May of 1097 and were warmly welcomed by Emporer Alexis. They then joined the main party of Crusaders and helped capture the city of Nicea.

The Crusaders began their campaign with a siege of the city of Nicaea. The walls of the city were several miles long and as it lay on the eastern shore of a large lake a section of the walls rose out of the water. The Crusaders surrounded the city but were unable to gain entry. Attempts at undermining the walls were unsuccessful. Towards the end of May the Turks attacked the Crusaders and inflicted heavy losses but were beaten back. When it was discovered the the city was getting supplies from across the lake the Emporer Alexius sent a number of boats to prevent any further shipments getting through. This was the final straw for the defenders inside the city and on June 19th moments before the Crusaders launched an attack they surrendered. But they did not surrender to the Crusaders but to the Emperor instead. This infuriated the Crusaders who were expecting a large haul of treasure from the city. Alexius treated the captured Turks well and allowed many to buy their own freedom. But the city was important for the Crusaders as control of it ensured they could not be attacked as they moved further east.

Spurred on by the find of the Spear of Longinus, the spear that was supposed to have pierced Jesus on the cross, the Crusaders emerged from the city of Antioch to face the Moslems. The Moslems were defeated, many being killed and many fleeing. After the batlle the ownership of the city was disputed. Bohemund and Raymond of Toulouse argued over its possession and after several months of debate Raymond accepted Bohemund's right to it. In truth, the city should have been handed over to Emporer Alexius.