The original Three Day Event was a competition for cavalry horse and Army officers and was introduced to the Olympics in 1912. The modern event became open to civilians at the 1952 Olympics after Britain had started horse trials at the Duke of Beaufort's home, Badminton. The modern format is based on the original exercises and covers three equestrian disciplines.

Dressage on the first day parallels the Parade ground. The horse must be obedient, graceful and submissive, the rider poised and elegant.

Next Day - Endurance Day - represents the battlefield. Imagine an officer is given a message to take to the front. Horse and rider trot off (Phase A: Roads & Tracks 5km). Interrupted by an enemy outrider they gallop away across the hedgerows (Phase B: Steeplechase 3.5km). Out riding the enemy they ease into a trot (Phase C: 2nd Roads & Tracks 9kms). Once on the battlefield, the horse and rider gallop across the field, jumping all in their way until the message is delivered (Phase D: Cross Country 6kms).

The next morning the horse is checked for its ability to carry on before taking a short cut back to base jumping the fences on the way.

The test is complete. The winner will have achieved the journey with grace, speed, stamina and athleticism, establishing the horse and rider as a trusting combination.

Current Three Day Events are classified according to their degree of difficulty and are awarded "Stars", with 1 Star being the easiest, up to 4 Star being the most difficult.