While it's more common for top-tier teams to participate in European competitions, several English second-tier football clubs, now known as the Championship, have also had their moment on the continental stage. These appearances often arise from winning major domestic trophies like the FA Cup or League Cup while playing outside the top flight.

One of the most notable examples is Wigan Athletic. In 2013, they defied the odds to win the FA Cup, defeating Manchester City in the final. However, their joy was short-lived as they were relegated from the Premier League just days later. Despite being a Championship team, Wigan qualified for the 2013-14 Europa League. Their journey included a group stage campaign against Rubin Kazan, Maribor, and Zulte Waregem.

Another instance is Birmingham City. They won the League Cup in 2011 against Arsenal, which secured them a spot in the Europa League for the 2011-12 season, even though they were relegated from the Premier League that same year. Birmingham City nearly made it out of their group containing Club Brugge, Braga and Maribor, missing out by just one point and beating Maribor (twice) and Club Brugge.

Sunderland experienced their only European season to date from the second tier of English football in 1974. They had won the previous season's FA Cup whilst still playing in the second tier, beating Don Revie's Leeds, and would be eliminated from the second round of the Cup Winner's Cup by Sporting.

Cardiff City, while a Welsh club, plays in the English football league system. They have a history of participating in European competitions as a second-tier side, thanks to winning the Welsh Cup, which granted them entry into the Cup Winners' Cup. Cardiff were regulars both in the lower tiers of English football and Europe since the Welsh Cup awarded a spot in the Cup Winner's Cup. In the 1967-68 season they dispatched Shamrock Rovers, NAC Breda and Torpedo Moscow to play Hamburg in the semis.

Millwall became the first team outside the Premier League to play an FA Cup Final in 2004, which they lost to Manchester United, in a game where the Blues were missing 16 players due to suspension or injury.

The instances highlight the possibility for second-tier teams to compete in Europe, usually contingent on exceptional cup performances. These campaigns offer memorable moments for the clubs and their fans, providing a unique opportunity to test themselves against international opposition.