Matilda finally decided to claim her birthright and challenge Stephen I for the English throne. Each side held the upper hand at various points between 1139 and 1146. At one point, Matilda captured the king and prepared to dethrone him. However, Stephen managed to regain control when his forces defeated Matilda and forced her flight. By 1143, a stalemate developed which lasted several years.
The civil war truly began with Matilda’s invasion of England on September 30, 1139. She immediately established her base of operations at Arundel Castle in West Sussex. King Stephen moved quickly to lay siege to Arundel. Stephen agreed to a truce and allowed Matilda to leave the castle. He had his rival trapped, but let her go. No one knows the reason behind Stephen’s actions. However, it is possible he did not wish to keep his army bogged down in a long siege while other enemies remained.
Whatever the reason for the king’s generosity, Matilda controlled a large swatch of his territory. The king pivoted to regain control of the land and stamp out her threat. However, he was forced to abandon his offensive to face a rebel force marching on London. Meanwhile, Ranulf of Chester plotted against Stephen because the king surrendered his lands to the Scottish. The king marched to capture Ranulf, but the nobleman escaped and declared his support for Matilda.
At the beginning of 1141, Ranulf moved on King Stephen militarily. The king laid siege to Lincoln Castle providing Ranulf and his allies a target of opportunity. The rebel cavalry began to encircle Stephen, but the king decided to fight on rather than flee. The king became a prisoner and the war appeared over.
Matilda met with Stephen and then locked the king away. Then, she made preparations for her coronation. The would-be queen gathered support of nobles and the church. Meanwhile, her husband, Geoffrey of Anjou, began the conquest of Normandy. Many Norman nobles switched sides rather than lose their property to a new monarch. Unfortunately for Matilda, Londoners supported Stephen and rose up in opposition. The empress fled to Oxford with her court.
Stephen’s fortunes changed in September 1141. His wife, Queen Matilda, led an army against Empress Matilda’s forces. The queen’s forces routed the empress and captured Robert of Gloucester. The two sides entered into negotiations to end the fighting. The women agreed to exchange the men, but little else came of the talks and the war continued into 1142.
Once again, it appeared the king had achieved a breakthrough. His army surrounded Matilda at Oxford Castle. The empress used the cover of darkness to escape across an icy river around Christmas. Her escape frustrated Stephen and the conflict continued. At the same time, Geoffrey of Anjou basically gained control of Normandy. A stalemate developed for the next few years.
Stephen and Matilda both came close to victory in their contest for the English crown. Matilda captured Stephen and even made coronation plans. However, a major defeat resulted in the king being released. Stephen had Matilda in his grasp more than once, but he managed to fumble. As a result, the war dragged on.