The organisation of Coast Defence was altered on many occasions from 1856 onwards. Portsmouth was manned by the 15th. Brigade which became the 21st. Brigade which in turn became the 6th. Southern Garrison Brigade. In 1889 this became the Southern Garrison Division.
Coast Artillery in the British Army found it difficult to produce enough men to man their guns in time of war and certainly the expense was prohibitive. As Gilkicker was essentially an auxiliary battery to Fort Monckton it was never considered necessary to quarter a permanent garrison there. At home there was never any intention to man all guns with trained artillerymen. They merely carried out the skilled maintenance of the guns and ammunition under the direction of the Master Gunner. Between 1856 and 1914 the reinforcements required on the outbreak of war to complete the manning of the coast defences was to be found from the various Corps of Militia and Volunteer Artillery. Gilkicker was often used for Militia training and was occupied by three batteries from the Hampshire Artillery Militia during their 28 days embodiment in 1871. Again on June 19th. 1885 No.5 Battery moved into Fort Gilkicker and was inspected by the Officer Commanding Royal Artillery Gosport District on July 6th. No.6 Battery relieved them on August 21st. leaving one N.C.O. and six gunners at the fort when they left on September 6th. The Brigade was disembodied on September 30th. leaving the fort empty.
Royal Garrison Artillery
Some regular Garrison Artillery batteries were stationed at Gilkicker between 1868 and 1890. The 5th. Battery 7th. Brigade R.A. were there from January to September 1872. In 1872 there were five Garrison Brigades with a total of 35 batteries 'at home‘. The 4th. Battery, 7th. Brigade moved from Fort Fareham to Fort Gilkicker on 12th. August 1880. They left Gilkicker for Shoeburyness gun practice on 26th. October 1881. They were replaced by 14th. Battery 11th. Brigade on 26th. October 1881. This battery became 2nd. Battery South Division Royal Artillery after the 1882 reorganisation when territorialisation of the Garrison batteries took place. The battery left Gilkicker on 1st. April 1882 for Fort Grange. The 10th. Battery Cinque Ports Division moved from Fort Grange to Gilkicker on 25th. January 1887. They left for Lydd on 30th. June 1888.
In June 1892 the Peace Emergency Garrison for defence
of the Isle of Wight and Portsmouth was converted into a
War Garrison for the purpose of practice. At Gilkicker
the 1st Hants Volunteer Artillery manned the guns,
whilst the Wicklow Artillery manned the guns at
1905 Fortress Portsmouth Defence Scheme
The Portsmouth Fortress Defence Scheme of 1905 called for Fort Gilkicker and Stokes Bay to be manned during the precautionary period by a regular battalion of infantry, consisting of 3 officers and 100 other ranks. Fort Gilkicker itself was to be manned by 3 officers and 73 men of the Northumberland Royal Garrison Artillery Militia from Berwick-Upon-Tweed. They were to travel by rail to Gosport (Fort Brockhurst Halt) and to march from there to Gilkicker. They were to be supplemented by 17 men from the District Establishment (including an Assistant Artificer, a storeman and a lampman) and 1 Sergeant Artificer from the Army Ordnance Corps with 3 officers and 22 men of the 4th. Battalion Royal Munster Fusiliers based in Killeny, in all, a total of 6 officers and 113 men.
Manning the two Battery Commands were 1 officer and 2 men (trumpeters and orderlies) of the Northumberland Royal Garrison Artillery. The Fire Command was situated at Alverbank. Each of the transmitting and receiving cells was manned by a detachment of 2 artillerymen. The Depression Range Finder Transmitters were to be manned by 2 men each with 10 men of the District Establishment to man the receiving dials. The two A guns were manned by 1 officer and 24 men with 2 men on the gun floor for shell supply and 2 men for cartridge supply. A further 4 men for each supply were located on the magazine floors. Two men were to be held in reserve. The B guns were to be manned by 1 officer and 20 men with 1 man on the gun floor for shell supply and 1 man for cartridge supply. A further 2 men for shell supply and 1 man for cartridge supply were located on the magazine floors with 2 men held in reserve.
Nine machine gun detachments were to be quartered at Gilkicker. Fort Gilkicker was also to accommodate a surgeon from the 1st. Hants Royal Garrison Artillery Volunteers where the recreation room was to serve as a dressing station and inspection room. He also served Fort Monckton.
In 1908 the Volunteers were abolished and the Territorial Force came into being. The Royal Garrison Artillery Coast Artillery Units of the Territorial Force were to man the coast defences rapidly and without delay in case of general mobilization.