Once William the Conqueror won, he began a building campaign of massive churches whose size completely dwarfed the smaller Anglo-Saxon buildings they were meant to replace. This had the effect not only of impressing upon the natives how different everything would be, but was also likely a way to atone for the bloodshed he had caused. This second reason was important, since Pope Alexander II in 1070 ordered him to do penance for the deaths he caused.
To that end, he ordered the construction of an abbey whose high altar should stand on the exact spot where Harold's standard fell, marking victory for the Normans. The abbey was dedicated to St. Martin of Tours (4th century), who had been a soldier before becoming third bishop of Tours and one of the most popular French saints. Despite that dedication, however, the place was referred to as Battle (or "Battel") Abbey, and the town of Battle developed next to it.
We don't know when exactly it was started, but in 1070 William invited 60 Benedictines to establish a monastery. His intent was that it would eventually house 140 monks. Enough was built for it to be habitable by 1076; it was finished in 1094. by William's . He endowed it with many estates, so that it became one of the richest monasteries in England.
When Henry VIII dissolved the monasteries, Battle Abbey was given to one of the king's friends, who demolished most of it and turned the remainder into a large manor house. Little of the original remains, but visitors are welcome, historical reenactments take place on the grounds, and a plaque and stone stand where (we suppose) the high altar once stood.
There is a slightly different story about the founding of Battle Abbey that also establishes a closer link to St. Martin of Tours. I'll tell you about it tomorrow.