Both King John and the English barons…

Both King John and the English barons had agreed to the Magna Carta peace treaty in 1215, but neither side has complied with its conditions.

Civil war had broken out shortly afterwards, with the barons aided by Louis of France, who has sent siege guns.

John in January 1216 marches against Alexander II of Scotland, who has allied himself with the rebel cause.

John takes back Alexander's possessions in northern England in a rapid campaign and pushes up towards Edinburgh over a ten-day period.

The rebel barons, supported by thousands of English subjects, respond by inviting Prince Louis of France to lead them: Louis has a claim to the English throne by virtue of his marriage to Blanche of Castile, a granddaughter of Henry II.

Philip may have provided him with private support but refuses to openly support Louis, who is excommunicated by Pope Innocent III for taking part in the war against John.

Louis's planned arrival in England presents a significant problem for John, as the prince will bring with him naval vessels and siege engines essential to the rebel cause.

John upon containing Alexander in Scotland marches south to deal with the challenge of the coming invasion.