Complex sentence: When Sibella, the great-granddaughter of the Norman leader Strongbow, was granted the manor in 1219, the local Brennan chiefs retreated to the hills and lived an independent life until the plantation of Castlecomer by Earl Strafford.
Split into simpler sentences: When Sibella, the great-granddaughter of the Norman leader Strongbow, was granted the manor in 1219. The local Brennan chiefs retreated to the hills and lived and independent life until the plantation of Castlecomer by Earl Strafford.