PLYMOUTH, DEVONPORT, and STONEHOUSE, are commonly called "The Three Towns," though they adjoin each other, and form one of the largest sea ports and principal naval and military stations in England, situated at the south west corner of Devon. They extend about three miles from east to west, and comprise, with their northern suburbs of Morice Town and Stoke. Plymouth is on the east, Stonehouse in the centre, and Devonport on the west; and their eastern, southern, and western sides, are skirted and deeply indented by the broad, deep, and extensive creeks and harbours in the estuaries of the Tamar and Plym, which meet in Plymouth Sound, and take the names of Catwater, Sutton Pool, Mill Bay, Stonehouse Pool, and Hamoaze; to the latter of which the great naval arsenal of Devonport Dock Yard presents its massive sea wall and numerous docks, slips, &c, in a semicircular range of more than half a mile, exclusive of the Gun Wharf, and the large Government Steam Yard on the north, opposite Torpoint, to which there is a steam ferry across the estuary of the Tamar.
Plympton St. Mary on the east side of the vale of River Plym is no village but those of Ridgway, Underwood, Colebrook. The Hemerdon House is the ancient seate of the Newnhams and Strodes, is now a farmhouse. Plympton hundred holds Fenton and Dunstone in Yealmpton. Plymouth was anciently called Sutton, and was a prebendal parish attached to the collegiate church of Plympton, till that church was converted into a priory, when Sutton was appropriated to it. When Exeter was created a town by the Romans, Plymouth was still non-existent. There were various settlements nearby, notably at Mount Batten and Stonehouse, but the Romans themselves are thought to have only passed through the area. It was not until the Saxon invasion that Plymouth started to emerge. They set up numerous Manors in the district of which Sutton (meaning 'South Farm'), on the northern shore of Sutton Pool, gave birth to Plymouth. It was only a poor fishing village over-shadowed by Plympton Priory. Most of our modern Plymouth was given to Judhel of Totnes Castle. The King also ordered a castle to be built at Plympton and this he gave to Richard de Redvers, whom he created Earl of Devon. The King himself kept control of the Manors of Sutton, King's Tamerton (to distinguish it from Tamerton that became Tamerton Foliot) and Maker. It was because of this quirk of history that the parish of Maker was in Devon until 1844 when it was transferred to Cornwall. The population of the entire area was probably less than 1,000. Sometime after 1106 King Henry I gave the Royal Manors to the Valletort family as a reward for services rendered at the battle of Tinchebrai in Normandy. The Valletort's endowed the new Plympton Priory when it was founded around 1121. The Prior's power over the area was later to cause a great deal of friction with the burgesses of the growing township of Plymouth. Meanwhile, Plympton was growing fast. Houses were built near the castle and the small township of Plympton Erle was gaining in importance. So much so that in 1194 it became a market town while Sutton was still little more than a village.
Plympton was the main centre of population until the mid-1300s. Its main industry was exporting Dartmoor tin and in 1328 it petitioned to become a Stannary Town on the basis that the tin could be loaded direct onto ships for export whereas at Tavistock it had to be transported by road to the River Tamar before it could be shipped. Although its petition succeeded, Plympton eventually lost its trade to Sutton when the river Plym silted up with the waste from the tin-streaming. Crispin Gill states that the name Plym Mouth was first used in the Pipe Rolls for 1211 when a shipload of bacon was despatched to Portsmouth and another of wine to Nottingham. Plymouth clearly grew in importance as a result of this trade and it became a market town on January 27th 1254, although the Prior of Plympton held the market rights. It led to claims and counter-claims about who was lord of the manor and an inquiry was held. The judge reached certain important decisions, namely that the original Sutton, on the north shore of Sutton Pool, was owned by the Prior of Plympton; that the so far undeveloped land to the south was owned by a John Valletort; and the port itself belonged to the King.