Louis controlling Westminster Abbey, he could not be crowned king because the English Church and the Papacy backed Henry. John's death had defused some of the rebel concerns, and the royal castles were still holding out in the occupied parts of the country. In a bid to take advantage of this, Henry encouraged the rebel barons to come back to his cause in exchange for the return of their lands, and reissued a version of the Magna Carta, albeit having first removed some of the clauses, including those unfavourable to the Papacy. The move was not successful and opposition to Henry's new government hardened. In February, Louis set sail for France to gather reinforcements. In his absence, arguments broke out between Louis's French and English followers, and Cardinal Guala declared that Henry's war against the rebels was a religious crusade. This resulted in a series of defections from the rebel movement, and the tide of the conflict swung in Henry's favour. Louis returned at the end of April and reinvigorated his campaign, splitting his forces into two groups, sending one north to besiege Lincoln Castle and keeping one in the south to capture Dover Castle. When he learnt that Louis had divided his army, William Marshal gambled on defeating the rebels in a single battle. William marched north and attacked Lincoln on 20 May; entering through a side gate, he took the city in a sequence of fierce street battles and sacked the buildings. Large numbers of senior rebels were captured, and historian David Carpenter considers the battle to be "one of the most decisive in English history". In the aftermath of Lincoln, the loyalist campaign stalled and only recommenced in late June when the victors had arranged the ransoming of their prisoners. Meanwhile, support for Louis's campaign was diminishing in France and he concluded that the war in England was lost. Louis negotiated terms with Cardinal Guala, under which he would renounce his claim to the English throne; in return, his followers would be given back their lands, any sentences of excommunication would be lifted and Henry's government would promise to enforce the Magna Carta. The proposed agreement soon began to unravel amid claims from some loyalists that it was too generous towards the rebels, particularly the clergy who had joined the rebellion. In the absence of a settlement, Louis remained in London with his remaining forces. On 24