St Mary's Island History Group


When the dockyard and island became one

Talk by Richard Roe on 9 September, 2013




The original idea for an extension to Chatham Dockyard was suggested in August, 1814, by John Rennie who was the leading engineer of the age.


The problem in the Dockyard was insufficient space for timber, storage and other materials.


John Rennie’s first idea was to acquire land on the Frindsbury side of the river, dam Chatham Reach, then create three basins along the river. This idea was turned down by the Admiralty.


It was then decided to look at the marshlands of St. Mary’s Island.


The first purchase of land was in 1821. Then in 1847 a further 19 acres were purchased, followed by 185 acres purchased in 1854. This meant that the whole of St. Mary’s Island was now in the hands of the Crown and the Dockyard.


It was decided to use convict labour in the building of the extension, so between 1854 and 1856 St. Mary’s Convict Prison was built. The prison housed approximately 1,700 convicts and a staff of 232 which included 117 armed wardens. The prison was demolished in 1898.


The three basins were lined with bricks. The convicts first drained and levelled 21 acres of marshland before installing the six brickmaking machines. The first brick was produced in 1866 and a total of 110 million bricks were made before the work was done.


Basin no.1 (now the Marina) and Basin no.2 were opened in 1871. Basin no.3 (now Chatham Docks) was opened in 1873.


While convicts were digging out Basin no.2 they came across a ship buried in the mud. It was 36 feet down in the creek and upon investigation it was decided that it was one of the Dutch fleet that had raided the Dockyard on the 19th July 1667.


The ship had mistakenly taken a route through St. Mary’s Creek, got stuck and had been abandoned. At the end of the investigation the convicts broke up the timbers and carried on building.



BASINS 1871 Convicts Excavating Large Basin


In Basin no.1 four docks were built (nos. 5, 6, 7 and 8).The first ship to use the docks was HMS Invincible, so Dock no. 5 became known as the “Invincible Dock”.


In 1871 the first phase of building was completed but it took until 1885 for the whole of the extension to be finished. An official opening took place on the 26th September, 1885.


The final cost of building the St. Mary’s Island Extension was in excess of

£2 million.