Lee Pearson made it 13 Paralympic golds as Great Britain retained the Para-equestrian team title which they have held since the Atlanta Games in 1996.
Solid rides from Pearson and Natasha Baker on Saturday had left GB in third place overnight.
And the final British rider Sophie Wells scored a superb 75.651% to move them up into the lead.
But with the Netherlands a big danger, they had an anxious wait before victory by 0.656% was confirmed.
Grade IV individual champion Sanne Voets finished on 78.200% but it left the Dutch on 229.249, behind GB’s winning total of 229.905.
“We didn’t think we would win gold and weren’t expected to,” said 47-year-old Pearson.
“We don’t have a horse on the team who’s done a championship before and two have never even been abroad.
“To be here, to compete and do as well as we have is a fairy-tale. The selectors have put great faith in us to send these young horses, which shows they do believe in us as riders to get the best score, and we’re grateful for that.”
Baker, who is now a six-time Paralympic champion, added: “We’re just so exceptionally proud of everything that our horses have done over the last few days – the way they’ve dealt with it so well and been such professionals.”
Wells, who was also part of the victorious team in both London and Rio, said that their previous success had helped play a part in this gold-medal win.
“This time we didn’t go in fighting for it because we didn’t think we were in the mix,” she said. “It just shows that maybe a different approach is good, especially for me on this horse.
“I’ve had to use every bit of my experience and it’s taken great resilience to even get here, but we have such belief in each other.”
The trio, along with Georgia Wilson, will hope to finish the equestrian events on a high in Monday’s individual tests to music (from 08:00 BST).