It's an election year in Canada. The country will head to the polls in October to render judgment on Prime Minister Justin Trudeau's government, either giving it a second term or sending it packing after four years in office.

But some voters will get a chance to offer their own verdicts much sooner. At least three byelections will be held in February in ridings spread across the country: York–Simcoe in Ontario, Outremont in Quebec and Burnaby–South in British Columbia. That last contest is the one NDP Leader Jagmeet Singh is hoping will give him a seat in the House of Commons.

Byelections don't always make history and, when they do, their importance often becomes clear only long afterwards. But these byelections could turn out to be significant events — by deciding the fate of a party leader, signalling the end of the NDP's orange wave, or measuring the depth of a new split in the conservative movement.

The byelection that took down a party leader

Arthur Meighen is certainly one of Canada's least illustrious prime ministers. He took over from Sir Robert Borden, the Conservative prime minister who led the country through the First World War, for about a year before meeting defeat at the hands of W. L. Mackenzie King's Liberals in 1921. He remained at the helm of the party for another two elections, getting a second stint as prime minister in 1926.

By 1941, Canada was again at war and the Conservatives were in need of Meighen's experience. The party had been dealt another crushing defeat by King's Liberals in 1940 and convinced Meighen to step back into the job. There was only one problem: Meighen hadn't had a seat in the House of Commons for 15 years, though he did occupy a seat in the Senate. That simply would not do for the leader of Canada's opposition.

Alan Cockeram, Conservative MP for the Ontario riding of South York, dutifully stepped aside to offer Meighen a shot at his seat. It was a safe Tory riding, having voted for the party in every election since its creation in 1904.

The Liberals opted to respect parliamentary tradition and not run a candidate against an opposition leader seeking a seat in the House. But King still wanted to see Meighen defeated, and so the Liberal party threw its weight (unofficially, of course) behind Joseph Noseworthy, candidate for the Co-operative Commonwealth Federation.

Arthur Meighen, seen here when he was briefly prime minister in 1920, failed in his attempted return to the House of Commons as leader of the Conservatives in a 1942 byelection. (Library and Archives Canada)

Noseworthy had finished a distant third in South York in 1940. But on a snowy Feb. 9, 1942, despite having Ontario Premier Mitch Hepburn and the provincial Conservative leader, George Drew, campaigning by his side, Meighen fell short by 4,426 votes.

Immediately, questions were raised about whether Meighen could hold on as party leader. The Toronto Daily Star wrote that Meighen's "ability, his intellectual honesty and his skill as a debater" were unquestioned, but "his popular appeal is a different matter altogether."

Meighen knew he was done. And the party was moving on, adopting a far more progressive platform than Meighen could support. He successfully persuaded John Bracken, Liberal-Progressive premier of Manitoba, to take his spot. One of Bracken's conditions was that the party would add "Progressive" to its name. And so, the Progressive Conservative Party was born.

Meighen's defeat in South York in 1942 was the last time a national leader met personal defeat in a byelection. That one loss helped set the Tories' course for the next 60 years. It's one byelection precedent Singh will not be looking to repeat in 2019.

Outremont and the rise (and fall) of the NDP in Quebec

In 2007, Outremont was one of the safest Liberal ridings in the country, having backed the party in every election but one over the previous century. So when Jean Lapierre resigned his seat, Liberal Leader Stéphane Dion saw an opportunity to parachute a hand-picked star candidate, Jocelyn Coulon, into the riding.

The Liberals met an unexpected challenge from the New Democrats, who had a star candidate of their own on the ballot — Tom Mulcair, a former environment minister in Jean Charest's provincial Liberal government. It was an ambitious candidacy for the NDP, which had only one victory in Quebec to its credit over its entire history.

Still, the Liberals were feeling the heat from Mulcair's candidacy. The party brought in some big names to help bolster the floundering Dion — including Justin Trudeau, at the time known only as the son of a former prime minister.

The breakthrough by Tom Mulcair (left) in the 2007 byelection in Outremont foreshadowed the party's surge in Quebec under Jack Layton (right) in the 2011 federal election. (Ryan Remiorz/Canadian Press)

But the New Democrats pulled off the upset; Mulcair won nearly half the vote and outpaced Coulon by almost 20 points.

The NDP's victory didn't immediately open the floodgates for the party in Quebec. But it gave the New Democrats credibility in the province. Mulcair held the seat again in 2008 as the NDP increased its share of the popular vote in Quebec to 12.2 per cent from 7.5 per cent in 2006.

That set the groundwork for the party's breakthrough in 2011, when Mulcair was joined by 58 other NDP MPs from the province. After taking over the party's leadership following the death of Jack Layton, Mulcair was only able to hold 16 of those seats in the 2015 federal election.

For Singh, the byelection this year in Outremont risks being a disappointing bookend to the story of the NDP's rise and fall in Quebec. The polls suggest all of the party's seats in the province could be at risk in this year's federal election. The byelection in Outremont should give us a sense of just how vulnerable those seats are.

Breaking up in public

The Progressive Conservatives went from a solid majority government to just two seats in the 1993 federal election, one of the most dramatic falls from power of any party anywhere in the democratic world. That the PCs were in trouble going into that election was obvious — but the scale of the defeat still came as a shock.

Two byelections years before, however, had signalled what was to come. In 1993, the PCs were defeated in large part because the two voting blocks that helped bring them to power in 1984 — Western Canadian conservatives and Quebec nationalists — broke off to support new parties: the Reform Party under Preston Manning and the Bloc Québécois under Lucien Bouchard.

Reform entered the House of Commons for the first time after Deborah Grey won the 1989 byelection in the Alberta riding of Beaver River, taking the seat away from the PCs. The Bloc — which formed itself out of a group of floor-crossing Liberals and PCs — won its first seat when Gilles Duceppe took the 1990 byelection in Laurier–Sainte-Marie.

Reform Party leader Preston Manning and MP Deborah Grey, a few months after Grey's 1989 byelection victory in the riding of Beaver River, which gave the Reform Party its first seat in the House of Commons. (Ray Giguere/Canadian Press)

In the 1993 federal election, the PCs lost all of their seats in Alberta and retained just one in Quebec — one of two seats they held nationwide — as Reform and the Bloc won the majority of each of those province's ridings.

Ten years later, attempts to re-unite the right were galvanized by another byelection. A vacancy in the Ontario riding of Perth–Middlesex was seen as a key opportunity for the Canadian Alliance — Reform's successor — to pick up a seat and present itself as the government-in-waiting after a decade of Liberal rule. Instead, the Alliance finished third, with the PCs narrowly squeaking out a win over the Liberals.

It was the last straw for Alliance Leader Stephen Harper, convincing him that the only way for his party to defeat the Liberals was to put aside its differences with the PCs. Within seven months, the Conservative Party of Canada was created.

The split on the right is unlikely to be so dramatic when Maxime Bernier's People's Party contests the upcoming byelections — the former Conservative MP's party is still languishing at single-digits in the polls. But the PPC doesn't need a significant amount of support to have a real impact on Conservative Leader Andrew Scheer's chances of becoming prime minister in the next federal election.

For now, the main electoral course will have to wait. But in the coming weeks, Canadians will get an intriguing appetizer in these byelections — a taste of what's to come in October's federal election.