sentences:  A Welsh Marcher Lord, Lord Lanstephan fought, along with his older brother William, and half-brother Robert FitzStephen, constable of Cardigan, under Robert FitzMartin at the Battle of Crug Mawr in Wales in 1136.Llansteffan Castle overlooks the River Tywi estuary where it enters Carmarthen Bay.It was captured by Maredudd ap Gruffydd in 1146 against the forces of Maurice FitzGerald and his brother William, Lord of Emlyn who were the leading Norman settlers of the region.