The 1st Battalion sailed on the Oriental on 22nd October 1899, and arrived at the Cape about 13th November. They were sent on to Durban, and along with the 2nd Royal Fusiliers, 2nd Royal Scots Fusiliers, and 2nd Royal Irish Fusiliers, formed the 6th Brigade under Major General Barton. The work of the brigade is sketched under the Royal Fusiliers, and that of the Natal Army generally under the 2nd Queen's.
At Colenso the losses of the battalion were trifling.
When General Buller made his second attempt against the Colenso position the battalion went out with Lord Dundonald to Hussar Hill on 12th February, and again on the 14th when the hill was finally occupied. All through the fourteen days' fighting the battalion took its share. On the 24th the Royal Fusiliers and Royal Welsh Fusiliers were holding some kopjes near Langerwachte under very heavy shell-fire and rifle-fire. On that day the Welsh Fusiliers lost Colonel Thorold, another officer, and 6 men killed, and 2 officers and 29 men wounded. The battalion was not with General Barton in the assault on Pieter's Hill at the eastern end of the position. In the fourteen days the battalion's losses were approximately 2 officers and 8 men killed, 2 officers and 60 men wounded.
Six officers were mentioned in General Buller's despatch of 30th March 1900, and 1 non-commissioned officer was recommended for the distinguished conduct medal.
In April 1900 the brigade was brought round to Cape Colony and concentrated at Kimberley. On 5th May the battle of Rooidam was fought, this battalion and the Royal Fusiliers being in the first line. The subsequent history of the Welsh Fusiliers is very similar to that of the 2nd Royal Scots Fusiliers, and reference is made to the notes under that battalion.
For their work in the very arduous pursuit of De Wet, in August 1900, the Welsh Fusiliers as well as the Scots Fusiliers were highly praised by Lord Methuen.
At Frederickstad between 15th and 25th October 1900 General Barton had a lot of very severe fighting, in which the battalion again gained great praise from the general and Commander-in-Chief. In these actions the battalion had about 15 men killed and 3 officers and 30 men wounded.
Twelve officers and 19 non-commissioned officers and men were mentioned in Lord Roberts' final despatch.
During 1901 the battalion remained in the Western Transvaal and took part in the very successful operations of General Babington. In his despatch of 8th May 1901, para 13, Lord Kitchener refers to an attack which was made on 22nd April by 700 Boers under the personal command of General Delarey upon a convoy passing between General Babington's camp and Klerksdorp; "the escort, however, being well handled, repelled the attack, inflicting a loss upon the enemy of 12 killed and 6 wounded". The escort was mainly from this battalion, and Colonel Sir R Colleton and two other officers were commended in despatches for their excellent work. One month before, General Babington had captured a Boer convoy and several guns, and on that occasion Sergeant Darragh gained the distinguished conduct medal for, "on his own initiative, keeping a very superior force of the enemy at bay in a most gallant manner".
On 23rd May 1901 another convoy going to Ventersdorp was very heavily attacked, but the enemy was driven off. A detachment of the battalion again formed part of the escort, and lost 1 man killed and 1 officer and 11 men wounded. On this occasion the wounded officer, Captain Hay, and 5 non-cominissioned officers and men gained mention for exceptional gallantry.
Towards the close of 1901 the battalion occupied the northern portion of the line of blockhouses running from Potchefstroom to the Kroonstad district.
That the Royal Welsh Fusiliers added to their reputation in South Africa is beyond doubt, and the fact that they gained sixteen mentions during the later stages of the war, after Lord Roberts left South Africa, proves they did not grow stale. In Lord Kitchener's final or supplementary despatch the names of 4 officers and 3 non-commissioned officers were added.