Asselin was born in Saint-Hilarion, Charlevoix, Quebec. His name is a combination of the French first name "Olivier" and the last name of Latin American independence leader Simón Bolívar. He did his primary studies in a Sainte-Flavie school and his secondary studies at the Séminaire de Rimouski. For financial reasons, his family emigrated to the United States in 1891. After a while working at the Coton Mills there, he worked for numerous newspapers in what was then called the "French Canadian" community. He was first journalist for Le Protecteur Canadien of Fall River, in 1894. A year later, he was editor of Le National of Lowell, Massachusetts and Le Jean-Baptiste of Pawtucket, Rhode Island. From 1896 to 1898, he was editorial secretary at La Tribune of Woonsocket. During the Spanish–American War, he undertook a first brief military participation, from 1898 to 1899. Demobilized in 1899, he moved to Montreal and contributed to various papers, including Les Débats. On August 3, 1902, he married Alice Le Bouthillier. From 1901 to 1903, he was secretary to Minister of Colonization Lomer Gouin. He stood as a nationalist candidate in Terrebonne during the 1904 election, then in Saint-James during the 1911 election. In 1907, after a session of the Legislative Assembly of Quebec had ended, he came down from the press gallery to confront Louis-Alexandre Taschereau, Minister of The Public Works, and future Premier of Quebec, on the Assembly floor. He was upset over an allegation the Minister supposedly made about him during the session, implicating him in an affair over a false telegram. Asselin told him it was false, but Taschereau refused to admit he made such an allegation. Asselin slapped him in the face, earning him a stay in jail. The imprisonment was notably criticized by Henri Bourassa. From 1902 to 1910, he worked closely with Henri Bourassa and collaborated with him in the founding of Le Devoir in 1910. He was President of the Saint-Jean-Baptiste Society of Montreal from 1913 to 1914. A nationalist militant, he set up the Ligue nationaliste in March 1903 and launched the newspaper Le Nationaliste a year later. It is during this time that he takes on him to defend the settlers right to cut trees and provide information to the Commission de la colonisation of 1904. In 1905, he began a campaign in favour of public compulsory education. The November 26, 1915, Sir Sam Hughes, Minister of Militia and Defence, offered Asselin the honorary rank of Colonel, which entailed raising a battalion for the Canadian Expeditionary Force. Asselin recruited men to form the 163rd Battalion, CEF, known as the "Poils-aux-pattes", made up of French-Canadian volunteers, and placed them under the command of Captain Henri Desrosiers, accepting instead the rank of Major. After training in Bermuda, the 163rd Battalion made its way to England, disembarking in December 1916, where the battalion was quickly dismantled and used to reinforce other depleted sections. Transferred to the 22nd Battalion, CEF, Asselin participated in the Battle of Vimy Ridge and the Battle of Acheville. However, he was later removed from the front after contracting trench fever. Alternately speaker and military attaché, Asselin found himself as a member of the Canadian Delegation at the Paris Peace Conference of 1918, which led to the Treaty of Versailles and the end of World War I. Asselin received the Légion d'honneur from France in 1919. In 1930, he became the editor-in-chief of Le Canada and founded, five years later, his own newspapers, named L'Ordre and La Renaissance. Olivar Asselin died in 1937, in Montreal, at the age of 62. He was entombed at the Notre Dame des Neiges Cemetery in Montreal.
