The Forth Royal Garrison Artillery and its successors were Scottish part-time coast defence units of the British Army from 1908 to 1956.

Although they saw no active service, they supplied trained gunners to siege batteries engaged on the Western Front during World War I.

[8][10][11] By 1914 these two units were responsible for the manning the following guns in the Forth defences: [12] On the outbreak of war the Forth RGA mobilised under the command of Lieutenant-Colonel H. O'Connor, VD.

[13] By October 1914, the campaign on the Western Front was bogging down into Trench warfare and there was an urgent need for batteries of Siege artillery to be sent to France.

[15] A draft of 50–60 men from the Forth RGA volunteered to serve together in 178th Siege Battery when it was formed at King's Park, Edinburgh, in June 1916.

[16] A number of other siege batteries formed in the Forth Defences in 1915–16 (89th, 90th, 118th,[a] 138th, 152nd, 153rd, 181st, 210th, 228th, 251st, 263rd, 293rd, and 311th) may also have included trained men from the Forth RGA among the recruits, although the Army Council Instructions did not specifically order this.

[26][27] When the infantry launched their assault at 07.30 on Z Day (1 July) the heavy guns lifted to successive targets, repeating the process six times.

[23][31] On 22 March 1917, 70th Siege Bty transferred to north to join 31st HAG with First Army,[23][31] which was preparing for the Battle of Vimy Ridge.

There was to be no preliminary bombardment or registration: when the battle began with a crash of artillery at 06.20 on 20 November the German defenders were stunned, and the massed tanks completed their overcome.

[23][31][39][40] 12th Brigade was part of IX Corps' Heavy Artillery in the fighting at Mont Kemmel, during the Battle of the Lys (the second phase of the German spring offensive) in April 1918.

[41][42] It then moved to Fourth Amy on 18 August 1918 in time for the Battle of Amiens and to participate in the victorious Hundred Days Offensive.

[41][43][44] For the next attack, the Battle of the Selle, IX Corps HQ selected important localities to be bombarded by 70th Siege Bty's heavy howitzers, for which 200 rounds of ammunition per gun were accumulated.

The corps attacked on 17 October, 'lifted forward' by two great belts of intense artillery fire, and a German counter-attack was hit by every gun within range.

The attack went in at 01.20 in moonlight, after the heavy guns had done the usual CB and harassing fire bombardments, and the results were extremely satisfactory.

[15] 108th Siege Battery was formed in the Forth Defences under Army Council Instruction No 397 of 21 February 1916 with a cadre of three officers and 78 men from the Forth RGA.

Just before Zero hour (00.30 on 23 July) the heavy artillery provided five minutes of intense bombardment of the western part of the village between the Bapaume road and the cemetery.

The Australian battalions attacking the village encountered little resistance and reached their objective before daybreak, though there was bitter fighting elsewhere.

The attack on this front was a complete success, and the German artillery was largely neutralised by the bombardment (later analysis showed that enemy gun positions had been fixed with 90 per cent accuracy).

The gunners removed the dial sights before abandoning their howitzers and those armed with rifles took up a position about 300 yards back.

On 26 and 30 August, during the Battle of the Scarpe, 78th Bde supported the Canadian Corps, with the heavy guns firing 600 yards (550 m) ahead of the creeping barrage.

A cadre of 50–60 volunteers was obtained for the battery from the Forth RGA and together with recruits from the depots it assembled at King's Park, Edinburgh, between 3 and 5 July.

It suffered heavy shelling and air attack, being forced to abandon its guns temporarily, but was able to withdraw when Third Army fell back from the dangerous salient.

[35][64][70][71] After the 'Great Retreat' 178th Siege Bty spent the next four months in front of Albert, behind the Ancre, which was the limit of the German advance.

The battery's FWD Model B gun tractors and lorries proved useful in the subsequent pursuit to the Hindenburg Line.

The battery rejoined Forth Heavy Regiment (as RA brigades were now termed) on 1 November 1938 and reconverted to the coast artillery role.

As the invasion threat receded, the coast defences were seen as absorbing excessive manpower and were scaled back, the gunners being redeployed.

[83][104][108][109][110] The following served as Honorary Colonel of the unit:[6][111] There is a bronze plaque in St Giles' Cathedral, Edinburgh, as a memorial to the 124 men of the Forth RGA who died in World War I.