Ten-man Manchester United came back from a goal down to defeat Crystal Palace 2-1 and win the FA Cup.
Jason Puncheon gave Palace a 78th-minute lead at Wembley Stadium which was cancelled out three minutes later by Juan Mata.
United defender Chris Smalling was red-carded in the first period of extra time.
But substitute Jesse Lingard then grabbed a sensational 110th-minute winner as United claimed a first FA Cup since 2004.
Lingard’s extra-time thunderbolt earned Manchester United a record-equalling 12th FA Cup.
“It is fantastic to win this title for the club, for the fans and also for me, because I now have won the cup in four countries, and not many managers have done that,” Van Gaal said.
“With 10 players, and we have played Tuesday evening also (beating Bournemouth 3-1), but we have deserved it, I think. It was a super goal, eh?”
Lingard told media “I saw it come across and it landed nicely for me. All I had to do was hit it sweet, and luckily I did that. As a sub you always have to be ready. Thankfully I was.”
It was United’s first FA Cup win since 2004, allowing captain Wayne Rooney and Michael Carrick to complete their domestic medal collections, and took them level with Arsenal, winners in 2014 and 2015, as the most successful clubs in the competition’s illustrious history.
But while Van Gaal celebrated his first trophy in English football, and United’s first major honour since Alex Ferguson retired in 2013, it may not be enough to keep him in a job following the club’s failure to qualify for the Champions League.
Instead United, who lost Marcus Rashford and Marcos Rojo to injury and Chris Smalling to an extra-time red card, will go into the Europa League, along with West Ham United, after United’s Wembley win freed up an additional qualifying berth.
Palace manager Alan Pardew, meanwhile, met with FA Cup heartbreak for the third time, having been on the losing side against United with the south London club in 1990 and overseen West Ham’s defeat on penalties by Liverpool in 2006.
“The players have given me everything,” Pardew said.
“We played with heart and passion. It was a great cup final. Manchester United did the same. It made for an enthralling tie and a game that could have gone either way.”