Between 13 May 1286 and 12 August 1289, Edward I crossed the channel to restore order in Gascony and mediate between Alfons, King of Aragon and Charles the lame, King of Sicily, Edmund acted as regent in England. When Rhys ap Maredudd of Dryslwyn captured Llandovery Castle in June 1287, Edmund suppressed the rebellion, taking Dryslwyn in September; Rhys, however, evaded capture and went into hiding. Edmund met the cost of this campaign with loans from Italian merchants of about £10,000. In June 1289 Edmund mediated between Humphrey de Bohun, Earl of Hereford, and Gilbert de Clare, Earl of Gloucester, in a dispute over the Welsh marches between their lands, and forbade de Clare to build a castle at Morlais in Brecknockshire. Edward's return to England was followed by an inquiry into wrongdoings by the government during his absence, and though several judges and officials were disgraced, Edmund was retrospectively pardoned for any forest offences and allowed to answer by proxy any complaints against his administration in Cornwall, where he was High Sheriff from 1289 to 1300.