By 1260, Warenne had joined the party of Simon de Montfort, but switched back to the king's side in 1263.
In April 1264, he and Roger de Leybourne were besieged by de Montfort at Rochester Castle.
In April of the same year Warenne was present for the Battle of Lewes (fought near his ancestral home, Lewes Castle).
After the capture of the king and Prince Edward he fled to the Continent, where he remained for about a year.
His estates were confiscated but were subsequently restored.
He returned to fight in the campaign which culminated in the Battle of Evesham, the Battle of Chesterfield and the siege of Kenilworth Castle.

Warenne served in Edward I's Welsh campaigns in 1277, 1282, and 1283.
In 1282 he received the Lordship of Bromfield and Yale in Wales.
A good part of the following years were spent in Scotland.
He was one of the negotiators for the 1289 treaty of Salisbury and for the 1290 treaty of Birgham, and accompanied the king on Edward's 1296 invasion of Scotland where he commanded the only major field action of that year in the Battle of Dunbar.
By 1260, Warenne had joined the party of Simon de Montfort, but switched back to the king's side in 1263. In April 1264, he and Roger de Leybourne were besieged by de Montfort at Rochester Castle. In April of the same year Warenne was present for the Battle of Lewes (fought near his ancestral home, Lewes Castle). After the capture of the king and Prince Edward he fled to the Continent, where he remained for about a year. His estates were confiscated but were subsequently restored. He returned to fight in the campaign which culminated in the Battle of Evesham, the Battle of Chesterfield and the siege of Kenilworth Castle.
Warenne served in Edward I's Welsh campaigns in 1277, 1282, and 1283. In 1282 he received the Lordship of Bromfield and Yale in Wales. A good part of the following years were spent in Scotland. He was one of the negotiators for the 1289 treaty of Salisbury and for the 1290 treaty of Birgham, and accompanied the king on Edward's 1296 invasion of Scotland where he commanded the only major field action of that year in the Battle of Dunbar.
John de Warenne, 6th Earl of Surrey