Great Britain won a 20th gold medal of London 2012 inside the dressage arena, surpassing Beijing 2008 for the team's best tally in more than a century.
Laura Bechtolsheimer, Carl Hester and Charlotte Dujardin took team gold ahead of Germany inside Greenwich Park.
The Netherlands finished third to take the bronze medal.
This is the best Olympic performance by a GB team since the 1908 London Games, where the hosts supplied almost one-third of the entrants and won 56 golds.
German-born Bechtolsheimer said taking gold was a "very emotional" experience.
"It wasn't just about beating the Germans. It was about beating everyone else which, in Olympic history, Britain's never done in the dressage," she said.
"So to come here and win any medal would have been amazing but to come here and win gold, I don't think it's sunk in completely yet. But it's an incredible feeling for all three of us and I think we're all really proud of each other and of our horses."
Britain's dressage team have been an up-and-coming force in the equestrian discipline, which tests understanding between horse and rider as they complete manoeuvres inside an arena.
They finished fifth at Beijing 2008 but confirmed their potential for London 2012 with victory in last year's European Championships.
The horse is as important as the rider, if not more so. Hester's Uthopia, Bechtolsheimer's Mistral Hojris - better-known as Alf - and Dujardin's Valegro have now proved, on the biggest stage, that they are three of the best.
Britain's team average of 79.979 beat Germany's 78.216 as each of the three British riders defeated their German equivalent in what became a straight fight between the two.
First to compete in the dressage and going in the individual event only was Richard Davison on Artemis, who let out a disappointed sigh at the end of their outing. The duo scored 70.524 and failed to progress.
For Hester, 45, it was a different story. Buoyed by an excellent start, he and Uthopia produced 80.571, three full marks clear of opening German rival Dorothee Schneider on Diva Royal.
Bechtolsheimer and Alf followed it with 77.794, again outscoring German counterpart Kristina Sprehe with Desperados, meaning the destination of gold came down to fellow 27-year-old Dujardin.
Germany, the defending champions, were the team to beat heading into the Games. Eighteen months ago, German owners spent a fee believed to exceed £10m in purchasing star dressage horse Totilas, the 2010 world champion, from the Netherlands.
But German rider Matthias Rath, the ex-boyfriend of Britain's Bechtolsheimer, came down with glandular fever prior to the Olympics. Both he and Totilas were withdrawn as a result, damaging Germany's chances of overhauling the host nation.
In the absence of that partnership, Dujardin and Valegro seized their chance to become the stars of their home Olympics, setting an Olympic record last week before her second ride confirmed a memorable and historic first-ever team dressage title.
Her score of 83.286 put Britain well out of reach and into the record books for the most successful Olympic campaign in 104 years.