Since the Third Division was created in 1920 (it was extended into North and South sections in 1921, and became the Third and Fourth Divisions in 1958) only six other teams from that level have reached a semi-final.
In 1937, Millwall, then in the Third Division (South), were the first, beating three First Division teams - Chelsea, Derby County and the 1937 champions, Manchester City. Millwall, who finished eighth in their division that season, finally had their cup run ended at the penultimate hurdle, losing 2-1 to giants of the era, Sunderland.
In 1954, Port Vale took the Third Division (South) title and conceded only five goals at home (and 21 in all) along the way. In the FA Cup, they progressed to a semi-final against the First Division's runners-up, West Bromwich Albion, beating other top-flight clubs, Cardiff City and Blackpool, on the way. In the semi-final, Port Vale lost 2-1, and, ironically, the penalty with which West Brom beat them was scored by a former Vale player, Ronnie Allen.
A season later, York City contested Third Division's third (and fourth) semi-finals when they met Newcastle United, of the First, and took them to a replay before succumbing to defeat. Along the way, York, who finished fourth in their division that season, beat Blackpool (and Stanley Matthews) and Tottenham. They held the eventual cup winners, Newcastle, to a 1-1 draw at Hillsborough in the semi-final before losing 2-1 in a replay at Roker Park.
In 1959, it took another semi-final replay to dispatch the next Third Division FA Cup glory-seekers, Norwich City. They were 2,000-1 for the cup at the start of their campaign, and produced major shocks on their way to meeting Newcastle. In arguably the greatest giant-killing campaign by a Third Division Three, they beat Manchester United and Tottenham of the First Division (3-0 and 1-0, respectively) along the way. After holding Luton to a 1-1 draw at White Hart Lane, they lost 1-0 in the replay at Birmingham City's ground, St Andrew's.
In 1976, Crystal Palace, who finished the season third in the Third Division and were promoted, met Second Division semi-final opposition in the form of Southampton. Palace beat Leeds and Chelsea on their way to last four, and their campaign is best remembered for the sight of Malcolm Allison with a fedora on his head and champagne in his hand even in defeat. In a season for giant-killing, Southampton went on to beat Manchester United 1-0 in the final.
The last time a team from the Third contested a semi-final was in 1984. On that occasion, 20,000 supporters travelled from Devon to Birmingham, only to see their team, Plymouth, lose 1-0 to Watford at Villa Park. Earlier in the competition, Plymouth had only progressed to the third round after beating non-League Barking 2-1. In an otherwise poor season, Argyle finished sixth from bottom of their division.
Third Division FA Cup semi-finalists
1937 Millwall lost 2-1 to Sunderland
Final: Sunderland beat Preston North End 3-1
1954 Port Vale lost 2-1 to West Bromwich Albion
Final: West Brom beat Preston North End 3-2
1955 York City lost 2-0 in replay to Newcastle United
Final: Newcastle beat Manchester City 3-1
1959 Norwich City lost 1-0 in replay to Luton Town
Final: Nottingham Forest beat Luton 2-1
1976 Crystal Palace lost 2-0 to Southampton
Final: Southampton beat Manchester Utd 1-0
1984 Plymouth Argyle lost 1-0 to Watford
Final: Everton beat Watford 2-0