The Irish language was the main language of the native Irish people until the Great Famine.

The Great Famine killed about 1.5 million Irish people, and another 1 to 2 million immigrated to other countries such as America, the UK and Australia.

The Great famine was caused by a disease affecting potato’s (The staple food of any Irish peasant family at the time, as all other crops they grew such as carrots and cabbage and parsnips etc were forcefully exported by the British) at the time, called Blight.

Due to the huge hit on the Irish population, and further anglicization of Ireland during British rule of Ireland, the language effectively died out.

Only in isolated areas, such as the Aran Islands, was Irish still the primary language.

Then, in the late 19th century, a series of events known as the Gaelic Revival took place.

It was essentially a revival of of Irish traditions, customs, art, literature, legends and the Irish language.

After that, a very widely celebrated and renowned event called the 1916 Rising took place.

An Irish nationalist volunteer force (which my great grandfather funded, but that is another story) stormed many areas of Dublin.

They took the GPO (General Post Office), and many other important buildings

To cut it short, the British managed to beat back the revolutionaries while sustaining heavy casualties.

It is important to note that many of the Irish people at the time didn’t approve of the Rising.

But when the British executed the ringleaders of the Rising, the disapproved became martyrs.

Then after a civil war, in 1922 we got independence.

Since then, Irish has seen a huge revival

All Primary and Secondary schools in Ireland now teach Irish as a mandatory subject.

All road signs, sign posts, government buildings, IDF and An Garda Síochaná buildings have Irish on them.(edited)

I can now speak Irish relatively fluently.

And so can most Irish people.

So the language has by no means died.

Edit: added credit and removed the response
Credit: Clanmate lelop down at Club Soda Discord.