How about Union day?
In my ignorance I hadn't been aware that Romania had been divided... now I wonder if Germany has a Unification Day, because that's a country unified in my lifetime.
That's a bit off topic but yes, it's October 3.
Este în afară subiectului; dar da, este 3 octombrie.
2019-11-25 In English, a special day with a name is not "the" [X] Day, it is simply [X] Day. Reported as "something else". (However, DL did not reject my answer without "the".)
It's either "Unification Day" (accepted) or "the Day of Unification" (refused and reported), but it's not "the Unification Day". We don't use the article with names like this.