Started as Tyrone and managed to conquer Connaught and Munster by 1410, but now England has decided to station a 11k stack in Meath. Oh well, at least I have a personal union with France.
EDIT:
1 January 1422 Ireland is formed. I could have formed it a few days earlier but wanted to do it at the beginning of the year. Mostly it was casus belliless wars against the other OPM's, boosting my infamy way high. I got a conquest casus belli on England for Meath thanks to a mission though. Allied with Scotland and France I declared war on England who was allied with Portugal. After managing to grab Meath quickly I sat back and waited for my allies to beat England for me. England had reduced scotland to 3 provinces in a previous war so they were quickly destroyed and vassalised in this one. France however curbstomped England in Europe, but could not reach their island thanks to England's superior navy. Portugal sent one or two armies my way but I managed to white peace them. Then it was a waiting game, with England sending armies to my island, which I barely managed to destroy, not gaining enough warscore to gain Meath though. Then the best thing ever happened. England some sort of succession crisis, I'm not sure what but I think regency council. Pretenders popping up everywhere, I even managed to support some in London. Grabbing the opportunity I managed to sneak a few of my units into England without getting my fleet smashed, and destroyed enough of England's army to gain Meath. And so Ireland was born, thanks to England's last king dying to soon. Now I'm going to have to try to get the quest for the new world ASAP. Also France is really annoying, they keep insulting me, no doubt in a attempt to break the personal union.