Saturday marked the 199th birthday of Canada's founding prime minister, Sir John A. Macdonald, and the Sir John A. Macdonald Bicentennial Commission has been honouring the event with a series of a celebrations and its own Twitter hashtag, #SirJAM.

#SirJAM hashtag for Sir John A. Macdonald

Saturday would have been Sir John A. Macdonald's 199th birthday. (Sir John A. Macdonald Bicentennial Commission/Twitter)

But on Saturday, that hashtag was adopted by some Twitter users critical of Macdonald's legacy after a photo appeared on the #SirJAM Twitter feed that showed a couple attending a Sir John A. Macdonald Day event in Toronto dressed in "red face" (mock aboriginal dress).

Macdonald is known as one of the Fathers of Confederation and a "nation-builder" for his effort to build a national railroad stretching from one of the country to the other.

In a statement on his website marking Sir John A. Macdonald Day, Prime Minister Stephen Harper praised Macdonald for his "drive and ambition to unite and expand the country."

However, Macdonald's legacy is a dark one for many aboriginal people and others with an awareness of Canada’s dark history — one that includes some of the less praise-worthy events of Macdonald's tenure, such as the residential school system, the clearing of the plains, the mistreatment of Chinese railroad workers and the execution of Métis leader Louis Riel for high treason.