The 2nd Battalion sailed on the Mongolian about 21st October 1899, and arrived at the Cape about 16th November. Along with the 2nd Black Watch, 1st Highland Light Infantry, and 1st Argyll and Sutherland Highlanders, they formed the 3rd or Highland Brigade, first under Major General Wauchope and after his death under Brigadier General Hector Macdonald. The work of the brigade is dealt with under the 2nd Black Watch.
At Magersfontein (see 2nd Black Watch) the Seaforths saw their first fighting in the campaign. The regiment was not so severely cut up in the first outburst of fire as the Black Watch, but during the day its losses became very heavy, 5 officers and 53 men being killed or mortally wounded, 7 officers and 136 men wounded, and about 14 taken prisoners. The battalion moved to the right of the Black Watch after the firing began, and pushed very close to the trenches at the south-east of the hill; indeed it is recorded by 'The Times' historian that a party of the Seaforths actually got round to the east of the hill and ascended it from the rear. They were driven down, partly by the fire of the British guns, and were all either killed or wounded.
Three officers and 1 non-commissioned officer were mentioned in Lord Methuen's despatch of 15th February 1900 for great gallantry.
At Koodosberg in the beginning of February the battalion lost 1 officer and 3 men killed and 17 men wounded.
At Paardeberg (see 2nd Black Watch) the losses of the battalion were again appalling, 2 officers and 50 men being killed or dying of wounds, and 5 officers and 95 men wounded. Their advance that day, like that of the Black Watch and Argyll and Sutherland Highlanders, commanded the admiration of all onlookers, some companies of the Seaforths being specially praised for the way in which they pushed down to the river, crossed it, and worked up the right bank along with some of the Black Watch. In Lord Roberts' despatch of 31st March 1900, 3 officers, 2 of whom were killed, and 6 men were mentioned for their good work at Paardeberg.
During General Colvile's march from the Bloemfontein Waterworks to Heilbron some very severe fighting fell to the lot of the Seaforths, and they always earned the highest commendation of the divisional commander.
At Roodepoort, 28th May 1900, the battalion had to hold a position on the right. "They were heavily attacked from the right rear by a force which far outnumbered them", but "held their own all day". Colonel Hughes-Hallett was wounded, and the Seaforths had another officer and 15 men wounded.
In the operations round the Brandwater basin, when the Highland Brigade was acting as part of Sir A Hunter's army, the Seaforths again gained the encomiums of the general. In his despatch of 4th August 1900 Sir Archibald describes the taking of Retief's Nek with some detail. He remarks that on 24th July he ordered General Macdonald to bring up the Seaforths by a wide turning movement on the left of the Black Watch. The movement was completed successfully, "the Seaforths advancing with quiet gallantry and seizing the ridge".
When the enemy moved south of Bloemfontein three companies of the Seaforths were sent, about 13th October 1900, to occupy Jagersfontein and Fauresmith. Both places were attacked before daybreak on the 16th. At the former place the Boers got into the town in the darkness, indeed into the camp, but were driven out. The Seaforths, however, lost 12 killed and 1 officer and 5 men wounded. A portion of the battalion had fighting in the Redders-burg district, and moving south to the Rouxville Aliwal district, they operated there for a considerable time.
Twelve officers and 21 non-commissioned officers and men were mentioned in Lord Roberts' final despatch.
About the middle of February 1901 the battalion was taken to Victoria West, the enemy being active in Western Cape Colony at that time.
In the summer of 1901 the battalion furnished two companies as part of the infantry of a column working in the Eastern Transvaal under Major General Beatson and General Bindon Blood.
In March 1902 the battalion was employed to strengthen the railway line north of Kroonstad during General Elliot's great drives against the line, and shortly afterwards they were moved to Klerksdorp to strengthen the columns in the Western Transvaal in the efforts which were made to clear that district after the two mishaps to Lord Methuen's forces. The battalion furnished a guard to the Boer generals during the peace deliberations.
By a strange mischance Lieutenant E M Sutherland was killed near Frederickstad on 29th May, two days before the terms of peace were formally signed.
One officer and 1 private were mentioned by Lord Kitchener during the war, and in the final despatch the names of 6 officers and 8 non-commissioned officers were added.