3.15 Severn Fixed Defences

Incursion from sea, in Bristol's case by way of the Severn Estuary, was also considered and steps were taken to provide some protection against attacks on local shipping, port installations and lock gates by destroyers and torpedo boats, as well as deterring submarines from laying mines or landing small sabotage parties.

The answer lay in the installation of 'Emergency Coast Batteries', equipped with guns from 4" to 6" calibre kept in store by the navy since being removed from ships scrapped after the First World War. The beach battery at Portished, built to protect the entrance to Avonmouth Docks, was the first such installation to be become operational in the area, the battery containing two 6" guns, capable of engaging targets at up to 19.3 kilometers, two Coast Artillery Searchlights for observation and fighting and a single 26 cm Lyon Defence Searchlight for illuminating the beach. It fired its first calibration shots on August 22nd 1940, manning being initially undertaken by 365 (Independent) Coast Battery, Royal Artillery which was incorporated in 531 (Glamorgan) Coast Regiment on December 31st.

In October 1940 it was announced that the Severn Fixed Defences, a string of gun batteries, designed to protect the mouth of the Severn, would be established at Brean Down, on both Steep and Flat Holm, and on the Glamorgan coast at Lavernock Point. After some changes of plan to the proposed batteries on the Welsh side of the river the armament finally installed comprised two 6" guns at Lavernock and four dual role anti-aircraft/coastal defence 4.5" guns in two batteries on Flat Holm, these being able to engage surface targets at a maximum range of 11.27 kilometers. On the Somerset side 6" guns were used exclusively, Steep Holm possessing four such weapons, deployed in two batteries, while Brean Down boasted a further two guns. In addition, each site in the Severn Fixed Defences was equipped with two Coast Artillery Searchlights. By the end of 1941, with work on the new fortifications nearing completion two new units, 570 and 571 Coast Regiments, were formed which, within a year, had taken over full responsibility for the guns. 365 Battery at Portishead subsequently joined 571 Regiment, along with 366 Battery at Brean Down, which was declared operational on April 7th 1942.

Shortly after, on April 26th, it was announced that in order to conserve military personnel the guns in Portishead Coastal Battery would be almost entirely the responsibility of the Home Guard. This was confirmed on July 12th, and as the Admiralty required the guns to be constantly manned 80 men from the Portished Company of the 6th Somerset (Long Ashton) Battalion were ordered to be transferred, although a nucleus regular establishment of 2 officers and 28 other ranks from 184 Battery, 571 Coast Regiment, which were to take over at Portishead on August 20th, were to be retained. On December 6th the first Home Guard shoot was carried out and such practices continued to be undertaken for much of the following year.

However, as a result of the reduced threat to the country further economies were made in the autumn of 1943 when the Chiefs of Staff agreed that 71 out of the existing 260 coastal batteries could be declared redundant and placed in the hands of 'care and maintenance' parties, the bulk of their troops being posted elsewhere. Consequently, on October 20th, Lavernock, Brean Down and Steep Holm North ceased to be operational, followed shortly after by Steep Holm South, while 571 Regiment itself was disbanded on April 1st 1944, 570 Coast Regiment taking over its commitments in the area. Nevertheless, Portishead, with its large Home Guard contingent guarding Avonmouth, then handling the import of a vast amount of American equipment destined for Normandy, together with the two dual purpose anti-aircraft/coastal batteries on Flat Holm, were temporarily retained and practice firings continued until well after the Allied invasion had taken place. Towards the end of the year, however, even these installations were no longer required and Portishead ceased to be manned in November 1944 when the local Home Guard were 'Stood Down', while the two Flat Holm batteries, the last vestige of the Severn Fixed defences, were finally declared non-operational on December 18th, the last German bomber having long since left the area.