1970's
Because Ireland wants to be independent, so there is no reason for it to join another country.
early 1803th
Titanic was built in and launched from Belfast, Ireland. There wasn't a Northern Ireland until about a decade later.
Greece joined in 1981. Spain and Portugal joined in 1986.
Join the police.
Ireland is a separate country to England and has not joined it.
It is unlikely Ireland would join the Schengen Area unless the UK also joins. There is currently a passport-free area made up of Ireland and the UK. If Ireland were to join the Schengen passport-free Area without the UK it would mean passport controls on the border with Northern Ireland, which would be politically unacceptable.
Many Catholics, though not all, want Northern Ireland to join with the Republic of Ireland and become a united Ireland.
The United Kingdom.
Ireland first participated as a nation at the Olympics at the 1924 Summer Games in Paris.
For Ireland you can use ie.
Northern Ireland was part of Great Britain in WW2.