Portmagee was a village in County Kerry, Ireland on Earth.
In an alternate timeline accidentally created by Leonard McCoy saving Edith Keeler's life in March 1930, the Battle of Portmagee was fought in the village in May 1946. It was a crucial battle in that timeline's version of World War II as it liberated Ireland from Nazi occupation. This in turn led to the Allies retaking the United Kingdom. (TOS - Crucible novel: Provenance of Shadows)