The appellants had turned to Louis hoping for peace. The award was the signal for war. Many of the bishops and barons at once withdrew from Simon, who answered the deserters by declaring, “Though all should forsake us, I and my four sons will fight to the death in the righteous cause I have sworn to uphold, to the honour of the Church and the good of the realm. Many lands have I travelled, heathen and Christian, but nowhere have I seen such bad faith and falsehood as in England.”
London was enthusiastic in its support of the barons, and the Cinque Ports, the scholars of Oxford, and the Dominican and Franciscan friars were all on the side of reform. Chief among Simon’s supporters were Bishop Cantilupe, of Worcester, Gilbert, the young Earl of Gloucester, Hugh le Despenser, the justiciar, and Roger Bigod.
War began in March, when Prince Edward captured Gloucester, joined Henry at Oxford, and then seized Nottingham and Northampton, while Simon and the citizens of London attacked Rochester. Henry turned south, and encamped in full force near Lewes.
Again Simon laboured for peace, and in his own name and the name of Gilbert of Gloucester, the Bishops of Worcester and London went as ambassadors to Henry. Simon offered £30,000 to the king if he would make peace and keep to the Provisions of Oxford, and assured him that he had taken up arms not against Henry but against those who were “not only our enemies, but yours, and those of the whole kingdom.”
The king treated the proposal with scorn, and Prince Edward added an additional message of contempt.
On the 14th of May the battle of Lewes was fought and won by Simon, “through a singular conjunction of skill and craft on the one side, and rashness and panic on the other.”[47]
The Earl of Leicester went into the battle fighting for his country and his oath, and with the exhortation to his men “to pray God, if this our undertaking be pleasing in His sight, to give us might to fulfil the same, serving Him as good knights.”
The stout old Bishop of Worcester blessed the troops, “who had among them all but one faith, one will in all things, one love towards God and their neighbour, so that they feared neither to offend the king nor even to die for the sake of justice, rather than violate their oaths.” (Matthew of Westminster.)
At the end of the day the defeat of the royalists was complete, and the king, Prince Edward and his kinsmen were prisoners.
Then peace was made, Henry once more swearing to keep the charters and articles of Oxford, to employ no aliens, to submit the Provisions to arbitration again, to live thriftily till his debts were paid, and to give his son Edward and his nephew Henry as hostages for good behaviour till a permanent reform in the constitution was made. Early in June these terms of peace were proclaimed in London, to the general satisfaction, and on all sides the people shouted their thankfulness to Simon.