There is some variation on the spelling of Gernonstowne. On various maps and other documents it is spelled Gernonstowne, Gernonstown, Gernon's-Town, Gormanstown, Germanstown, Garlandstown, Garland, etc. Irish road signs show the English as Castlebellingham while the Irish translation still refers to baile an Ghearlanaigh - or Gernonstown. It was not called Castlebellingham for at least forty years after the purchase. The name does not appear on any document before the year 1700. About 1710 it began to appear in journals and other sources to be called Castlebellingham.
The castle was occupied by troops and burned down in the autumn of 1689 by King James II in revenge for Colonel Thomas Bellingham being a guide for William III, prior to the Battle of the Boyne. It is said that King William's armies camped the night before the Battle of the Boyne in the grounds of the castle.
Over time Castlebellingham became known as an important gathering point in the county. Fairs were held there every year. A church was constructed next door to the castle and graveyard with a family vault was built. The Bellinghams became one of the most powerful and influential family in the county. For over a hundred years a Bellingham held the seat in Parliament for county Louth.
Records also note Castlebellingham for having "the best malt liquor" in Ireland. Apparently a brewery was built on site about 1770 and belonged to an O'Bryen Bellingham. For a number of years a brewery partnership ran their liquor business. The brewery is still there but now houses the "button factory" or Smallwares Ltd. The brewery was the main supplier of drink to the Boer War troops.
A history of the parish, dated 1908, states that the impressive Calvary standing close to the Castle was erected by Sir Henry Bellingham as a monument to the memory of his first wife Lady Constance.
Castlebellingham was the ancestral home of the Baronet until about the late 1950s when it was eventually turned into a hotel called the Bellingham Castle Hotel which remains today. The last Bellingham to live there was Brigadier General Sir Edward Bellingham, born in 1879, who was the last Lord Lieutenant and Guardian of the Rolls (Custos Rotulorum).