John de Courcy was born in Somerset in 1150. His family were a good Norman pedigree and his ancestors fought alongside William the Conqueror in the Battle of Hastings in 1066.
John wasn't the oldest in his family, so wouldn't inherit any land. He wanted to have a good life so he became a knight and, in 1171 sailed across from England to Ireland with the Norman invading forces.
The Normans conquered Leinster and John stayed in Dublin for a few days, but he was getting bored. He wanted land of his own, so he decided to move north with 22 knights an 300 foot soldiers - without King Henry's permission.
John's army was very quick, marching thirty miles a day! They made their way up the back of the Mourne Mountains and took Downpatrick by surprise. After two fierce battles, John's army defeated the last King of Ulster, Rory MacDunleavy.
John's army conquered most of Down and East Antrim. He started to build castles to protect his lands. He claimed he found St. Patrick's bones in Downpatrick. He printed coins with St. Patrick's head on one side and his head on the other. This angered Prince John of England. In 1180 he married Affreca, daughter of the king of Mann, which meant his kingdom wouldn't be raided by the Vikings.
King John of England ordered Hugh de Lacy, ruler of Meath, to invade de Courcy's Kingdom. Hugh invaded and succeeded, defeating de Courcy's army. John fled and spent the rest of his life In poverty in Europe. Hugh was awarded de Courcy's lands as a reward.