AH cliché/mistake commonly (but not exclusively) made by misinformed Americans. Possibly thanks to the 400,000,000 billion trillion Americans claiming descent from Ireland, a view persists that Ireland is in fact a vast would-be global superpower that has only been prevented from achieving its place as dominant force on the globe by Anglo-Saxon perfidy. However, this is all just hyper-optimistic and ill-informed wish fulfilment.
The fact that Ireland can support perhaps ten million people at best, has spent virtually its entire history balkanised, and ceased to be a centre of civilisation after the early Dark Ages, tends not to dent these views. (See also: Leej ).
A variation on this is maps where a united Ireland is always present, regardless of what the rest of the map looks like (anything from a surviving Roman Empire to otherwise identical to OTL).
The most notable example is the Empire of All Ireland from the Map Continuation project, even though it's taken seriously.