Maria I of Portugal did not live to see the 5 October 1910 Revolution and she was Portuguese.
The establishment of the Portuguese Republic was the result of a coup d'état organised by the Portuguese Republican Party which , on 5 October 1910 , deposed the constitutional monarchy and established a republican regime in Portugal . The First Portuguese Republic ( Primeira República ) spans a complex 16-year period in the history of Portugal , between the end of the period of constitutional monarchy marked by the 5 October 1910 revolution and the 28 May coup d'état of 1926 . Dona Maria I ( English : Mary I ; 17 December 1734 -- 20 March 1816 ) was Queen of Portugal , Brazil , and the Algarves .