The earliest documentary reference to Mostar as a settlement dates from 3 April 1452, when Ragusans from Dubrovnik wrote to their fellow countrymen in the service of Serbian Despot Đorđe Branković to say that Vladislav Hercegović had turned against his father Stjepan and occupied the town of Blagaj and other places, including "“Duo Castelli al ponte de Neretua.”".