In the wake of the Dunkirk evacuation, and the successful invasion of Norway Germany felt like it was invincible, one idea that got floated was an invasion of ireland. The idea was that all it would take was one quick push towards dublin and the neutral government of Ireland would fall, and be easily replaced by a facist government that would help them bring and end to the decadent british empire and make operation sea lion a success.
The force that was sent out was small, fast, and landed on Irish shores while the british were more concerned about an attack on great britian and then they marched to dublin. The Irish milatary used obsolete equipment, they were not veteran troops, and their training was haphazard at best, but they held firm and dispite some very ugly defeats and massacers.
(See the rape of cork)
The Irish defeated the nazi's and then declared war on germany.
But what if the Nazi's didn't get victory disease? What if they didn't attack neutral Ireland how would this have changed the war?