The Senators have had a hot and cold relationship with the NHL post-season over the years.

The patience of fans was tested during four years of playoff losses to the Toronto Maples Leafs, a President's Trophy-winning season ending much too early and a quick run through the Eastern Conference to the Stanley Cup Finals that ended abruptly to a much stronger Anaheim team.

But through those disappointments, there have been a few huge -- and sometimes surprising -- playoff achievements by the Senators, though it's hard to argue this year marks the most impressive accomplishment yet.

5 Ottawa defeats Montreal in 5 (2013)

The Senators' run as perennial playoff contenders was behind them when they met the Canadiens in the first round of the 2013 playoffs. In a series that set the tone of the rivalry in the seasons that followed, Ottawa out-played and out-coached a Montreal team that lost its cool early and couldn't get it back. The series, the official signal the Battle of Ontario had become old hat, even included a line brawl and Brandon Prust's now famous line about former Senators coach Paul MacLean that spawned a line of "Don't f--- with the Walrus" T-shirts. Unfortunately for Ottawa, the Senators fizzled in Round 2 and MacLean never got his groove back.

4 First playoff series win (1998)

After making the playoffs for the first time the year before, the Senators took the next step in 1997-'98 when they won the club's first-ever playoff series against the heavily-favoured New Jersey Devils. Ottawa entered Round 1 as the eighth seed and finished 24 pack of the top-ranked Devils.

Bruce Gardiner scored the overtime winner for Ottawa in Game 1 in New Jersey to give the Senators a surprise series lead. Alexei Yashin would score in OT in Game 3 and Daniel Alfredsson had a hat-trick in Game 4. Ottawa ultimately won the series in six games thanks to the strong play of goalie Damian Rhodes.

3 Sens clinch first playoff spot (1997)

After the early years spent in the league basement, the Senators clawed their way into the post-season for the first time in 1997 and like 2015 edition, it came down to the last game of the season on April 12. Late in the third period of a scoreless game, Steve Duchesne's goal earned Ottawa the 1-0 win and clinched the franchise's first playoff spot. Ottawa would ultimately lose in seven games to Buffalo, but the Senators would go on to make the playoffs for the next 10-straight years. It was a huge moment for the franchise but not a shock; Ottawa had significantly improved under Jacques Martin and the playoffs were the next step in the franchise's growth.

2 Alfie sends Ottawa to the finals (2007)

After being picked to win the Stanley Cup and coming up short, Daniel Alfredsson scored what still might be the biggest goal in franchise history: The overtime-winner against the Buffalo Sabres in Game 5 of the Eastern Conference finals. The captain skated the puck over the Buffalo blue line and snapped a shot past Ryan Miller that would land the Senators in the championship series for the first time, quickly getting mobbed by Jason Spezza and Dany Heatley as the rest of the team spilled onto the ice. The only reason this isn't at No. 1 is it came at a time when Ottawa was expected to contend for a title, especially after blowing through the Eastern Conference in 15 games. Unfortunately for Ottawa, the five-game series trend continued into the finals against Anaheim and the Senators wound up on the wrong side of it.

1 Hamburgers, anyone? (2015)

Even the media was running out of things to ask the out-of-nowhere goalie sensation during what was a historic run to the playoffs. The only thing more impressive than Andrew Hammond's emergence as a top goalie has been his calm and measured reaction to the whole crazy situation. The 27-year-old AHL goalie was forced into duty when Craig Anderson and Robin Lehner both went down with injuries, defeating the Canadiens and then backstopping the Senators to a franchise-first sweep of California. Suddenly, there's no goalie controversy as Ottawa heads to the post-season, it's just not the guy everyone had their money on at the beginning of the year.