Irish king Fergus Mór mac Eirc, supposedly shipwrecked off the northeastern coast of Ireland, gives his name to a town on the north shore of Belfast Lough called Carrickfergus ("Rock of Fergus").

The historicity of Mór is doubtful.

John de Courcy, of Stoke Courcy, in Somerset, had come came to Ireland around the year 1171 as part of the Norman invading forces, brought in as mercenaries working for Dermot MacMurrough, the ousted King of Leinster, to help him regain his position as King.

John is very ambitious and wants lands for himself.

He had decided to invade the north of Ireland which was controlled by the Irish clans.

He assembles a small army of twenty-two knights and three hundred foot soldiers in early January 1177 and marches north at the rate of thirty miles a day, skirts the back of the Mourne Mountains and takes the town of Dun de Lethglas (later Downpatrick) by surprise.

After two fierce battles in February and June 1177, de Courcy defeats the last King of Ulaid, Ruaidrí Mac Duinn Sléibe.

He has done all this without the permission of his king, Henry II.

After conquering eastern Ulster, he establishes his capital at Carrickfergus, where he builds an impressive stone castle.

He marries Affreca, daughter of Godred II Olafsson, King of Mann.

It is likely that the marriage, as in the case of many kings and those aspiring to be kings during this age, is political, to seal an alliance with her father, who pays homage to the King of Norway.

Edward Bruce, brother of Robert, had in 1315 invaded Ireland with six thousand men in pursuit of some hereditary claim to the earldom of Ulster.

After routing the earl’s forces near Connor and gaining the allegiance of the inhabitants of Connaught and West Meath, Edward is crowned High King in 1316.

Many Anglo-Irish support him, increasing his power base.

Sorley Boy visits Scotland immediately, then appears in Carrickfergus to overawe Tyrone and the Glynns.

Elizabeth, on advice from Leicester, commands Essex to “break off his enterprise” in 1575.

Essex now switches tack, having struck a deal with Turlough Luineach O'Neill, and defeats Sorley Boy around Castle Toome, where the Bann flows out of Lough Neagh.

Essex has to withdraw to Carrickfergus for lack of provisions, but he now orders a follow-up operation, with the intention of driving the Scots from Ulster.

Under the commands of John Norreys and Francis Drake, an amphibious strike force of eleven hundred and fifty men in three frigates proceeds by sea from Carrickfergus to ...

...Carrickfergus and ...

A French force consisting of the ships Maréchal de Belle-Isle, Terpsichore and Blonde, carrying  six hundred French troops, lands in Carrickfergus, Ireland, under the command of the Privateer François Thurot, overwhelms the small garrison of the town, and captures its castle.

When word of the capture reaches Dublin, a small force of dragoons is dispatched by the Lord Lieutenant Duke of Bedford, who fears, incorrectly, that it is a feint to draw British forces to the north while a main French force is to attack Cork or Dublin.

Thurot holds the town for five days, menacing nearby Belfast and demanding supplies and a ransom.

In the face of the mobilization of large numbers of local militia under General Strode, and the appearance of a Royal Navy squadron off the coast, Thurot re-embarks his force and departs the town.

Thurot will be subsequently killed during the Battle of Bishops Court, but his feat in landing on enemy soil is widely hailed in France and he becomes a national hero, partly because his perceived daring is in sharp contrast to the incompetence shown by French naval officers at the recent Battle of Quiberon Bay.