Sunderland was a significant shipbuilding location and at one time produced about 25% of the new vessels built in England.
Sunderland was classified as a C Class Commercial Port in 1905 and it was thought that one battery of two 6-inch BL guns would be sufficient defence.
The geography of the harbour area did not allow a single battery to cover the whole harbour, so it was recommended that there be two batteries, one to the North and the other to the South in the Hendon area.
The Northern Battery was Rocker Battery, which lay adjacent to the later Abbs Battery.
Wave Basin Battery was built in 1860 inside the actual harbour area.
These two batteries were armed with RML guns and appear to have received a low priority with regards to upgrading.
