[2] Prior to the merger, there was an extreme drop in public support for Res Publica after the government led by Juhan Parts was forced to step down, and Pro Patria had also been relatively marginalised after the fall of their own governing coalition.

On 4 April 2006, representatives from the Pro Patria Union and Res Publica decided to merge the two parties, which took place officially on 4 June 2006.

Although originally the name For Estonia (Eesti Eest) was considered for the newly formed party, it was rejected, and the provisional name was used until the new name was adopted in 2018.

This cooperation was retained up until 2014, when the Social Democratic Party replaced The Fatherland as junior coalition partner.

It joined the Reform Party and Social Democrats to form the government under Taavi Rõivas.

[11] On 7 November 2016, the SDE and IRL announced that they were asking Prime Minister Taavi Rõivas to resign and were planning on negotiating a new majority government.

[15] On 26 June 2017, Tsahkna and MP Marko Mihkelson announced that they were leaving the party, dropping the amount of IRL MPs to 12.

[25][26][27] In June 2024, Isamaa was the biggest party of Estonia in European parliament elections with 21,50% of the vote.