Battles involving England - Stephen and Maud Wars
King Henry I died in 1135. His only son had already died in 1120. Henry had named his heir to be his daughter Matilda (sometimes known as Maud) and required his barons to swear allegiance to her. However, the barons did not want a woman to become monarch of England. Henry's nephew was Stephen, who rushed to London when Henry died, and was elected king by the citizens of London. He seized the treasury, and had the support of many barons. Some still supported Matilda. In 1139, Matilda entered England, and there followed decades of civil war, with neither side able to win. It is called the Anarchy. The Anglo-Saxon Chronicle described it as a time when "Christ and his saints slept", and "more than we can say, we suffered 19 winters for our sins".
Battle of Lincoln 1141 (location)
A supporter of Matilda, Ranulf of Chester captured Lincoln Castle. Stephen attacked the castle. Ranulf managed to escape and with his father-in-law, Robert of Gloucester defeated Stephen at the Battle of Lincoln February 1141. Stephen was made a prisoner at Bristol, and Matilda temporarily ruled from London. However, in September 1141, Robert of Gloucester was later taken prisoner by the supporters of Stephen, and Robert and Stephen were both freed as a prisoner exchange. So back to square one again.
Siege of Oxford 1141 (location)
In the winter of 1141, Stephen besieged Matilda in Oxford Castle, and if he had captured her, he might have won the war. But she escaped over the snow, camouflaged by being dressed in white. So back to square one again.
Stephen had hoped that his oldest son, Eustace, would suceed him, but Eustace died in 1153. Matilda's son, Henry of Anjou, was now adult, and invaded England to join the war. Stephen was in poor health by this time. In November 1153, Henry and Stephen signed the Treaty of Wallingford (also known as the Treaty of Winchester), where Stephen recognised Henry as heir to the throne. In 1154, Stephen died, and Henry II became king.
Wikipedia (external site) for further information - Battles index