By the First World War, the guns installed at Hurst Castle in the 1870s were obsolete.
The castle retained seventeen of them, as historian Coad states, wired up together "like a collection of elderly blunderbusses", but the fort depended on its newer quick-firing weapons.
During the war, Hurst's armament was controlled from Needles Battery, where a Fire Command Post, equipped with telegraphy, had been established.
After the war, the guns were removed from the 16th-century part of the castle, which was passed into the national collection of the Ministry of Works in 1933, although some modernisation of the rest of the fortification took place in the 1930s.
The "low light" was replaced by a new iron lighthouse in 1911.

During the Second World War, Hurst was re-armed in 1940 with two 12-pounder (5.4 kg) guns and a unit of the Isle of Wight Rifles was stationed there, controlled from the Fire Control Needles.
Searchlights and two more 6-pounder (2.7 kg) guns followed the next year, when the 37-strong detachment was retitled the 129 Coastal Battery Royal Artillery, followed by the installation of Bofors anti-aircraft guns.
A tower, called the Director Tower, was built along the west wing.
As the war progressed, the weapons were stood down and the battery finally closed in July 1945, with most of the weapons being removed after the war.

In 1956 the whole of Hurst Castle was transferred to the guardianship of the Ministry of Works.
During the 1970s, the additional concrete protection added to the south bastion in the 1880s was removed.
When the government agency English Heritage was formed in 1983, it took over the control of the castle.
In 1996 the Friends of Hurst Castle took on the day-to-day management of the castle, with English Heritage continuing to run other aspects of the site.
As of 2015, the castle received around 40,000 visitors a year.
The castle is protected under UK law as an ancient monument.
The High Lighthouse built in 1867 continues in use, and is protected as a grade II listed building.

The spit is subject to coastal erosion which has gradually pushed the spit towards the shore, a process which has eaten away at the remnants of the 1852 west wing battery and barracks, and has exposed the foundations of the later fortress on occasions.
This erosion has increased significantly since the 1940s, due to the construction of groyne barriers at nearby Bournemouth and Christchurch which prevented the natural renewing of the spit with pebbles washed from local cliffs.
Erosion caused fresh damage to the eastern end of the castle in early 2013, leading to renewed concerns.
Government efforts began in the 1960s to try to stabilise the spit in its current position, both to protect the castle and neighbouring towns, with over 900,000 tonnes (990,000 tons) of gravel being laid down in the 1990s, and is continuing in the 21st century.
The spit and the adjoining coastline is protected as an SSSI.
By the First World War, the guns installed at Hurst Castle in the 1870s were obsolete. The castle retained seventeen of them, as historian Coad states, wired up together "like a collection of elderly blunderbusses", but the fort depended on its newer quick-firing weapons. During the war, Hurst's armament was controlled from Needles Battery, where a Fire Command Post, equipped with telegraphy, had been established. After the war, the guns were removed from the 16th-century part of the castle, which was passed into the national collection of the Ministry of Works in 1933, although some modernisation of the rest of the fortification took place in the 1930s. The "low light" was replaced by a new iron lighthouse in 1911.
During the Second World War, Hurst was re-armed in 1940 with two 12-pounder (5.4 kg) guns and a unit of the Isle of Wight Rifles was stationed there, controlled from the Fire Control Needles. Searchlights and two more 6-pounder (2.7 kg) guns followed the next year, when the 37-strong detachment was retitled the 129 Coastal Battery Royal Artillery, followed by the installation of Bofors anti-aircraft guns. A tower, called the Director Tower, was built along the west wing. As the war progressed, the weapons were stood down and the battery finally closed in July 1945, with most of the weapons being removed after the war.
In 1956 the whole of Hurst Castle was transferred to the guardianship of the Ministry of Works. During the 1970s, the additional concrete protection added to the south bastion in the 1880s was removed. When the government agency English Heritage was formed in 1983, it took over the control of the castle. In 1996 the Friends of Hurst Castle took on the day-to-day management of the castle, with English Heritage continuing to run other aspects of the site. As of 2015, the castle received around 40,000 visitors a year. The castle is protected under UK law as an ancient monument. The High Lighthouse built in 1867 continues in use, and is protected as a grade II listed building.
The spit is subject to coastal erosion which has gradually pushed the spit towards the shore, a process which has eaten away at the remnants of the 1852 west wing battery and barracks, and has exposed the foundations of the later fortress on occasions. This erosion has increased significantly since the 1940s, due to the construction of groyne barriers at nearby Bournemouth and Christchurch which prevented the natural renewing of the spit with pebbles washed from local cliffs. Erosion caused fresh damage to the eastern end of the castle in early 2013, leading to renewed concerns. Government efforts began in the 1960s to try to stabilise the spit in its current position, both to protect the castle and neighbouring towns, with over 900,000 tonnes (990,000 tons) of gravel being laid down in the 1990s, and is continuing in the 21st century. The spit and the adjoining coastline is protected as an SSSI.
Hurst Castle