The 2nd Battalion sailed on the Simla, on 28th November 1899, arrived at the Cape about 17th December, and were sent to Durban. Along with the 2nd Somerset Light Infantry and 2nd Middlesex they formed the 10th Brigade under Major General Talbot Coke, and part of the Vth Division under Sir C Warren. The 2nd Royal Warwicks and 1st Yorkshires sailed from England as part of the 10th Brigade, but the stress of events in the evil days of December 1899 forced the breaking up of the brigade, the two latter regiments being left in Cape Colony to share in Lord Roberts' work there.
The 10th Brigade took part in the march to Springfield and in the operations about Venter's Spruit and Spion Kop. The brigade was not seriously engaged until the 24th January, when the Dorsets and Middlesex climbed to the summit. The Dorsets did not go into the trenches nor on to the fire-swept plateau. The Middlesex did, and suffered severely. The combat on Spion Kop is dealt with under the 2nd Royal Lancaster, 2nd Scottish Rifles, and 3rd King's Royal Rifles, and the operations of the Natal Army generally are sketched under the 2nd Queen's. In General Warren's despatch of 1st February 1900 the Dorsets were mentioned as "rendering great service in carrying down a large quantity of ammunition in the dark which would otherwise have fallen into the hands of the enemy". The detachment which acted as burial party on the 27th under trying circumstances were also praised for their admirable discipline. The 10th Brigade were in the fighting between 13th and 27th February. On the 21st the brigade crossed the Tugela and occupied the Colenso position north of the river, but not without severe fighting, in which the Somersets lost very heavily. Up till the 27th the brigade held positions, chiefly between the Tugela and the Onderbrook, and were constantly under fire, except during the armistice on the 25th. Colonel Law was mentioned in the despatch of 30th March 1900.
After the relief of Ladysmith the Vth Division was put under General Hildyard. The division followed the railway line in the movement on Dundee, and when General Buller was ready to turn the Laing's Nek position the 10th Brigade got an honourable place. The brigade now consisted of the Dorsets, Middlesex, and 1st Dublin Fusiliers, the Somersets having gone to Cape Colony. On 6th June General Coke occupied Vanwyk's Mountain preparatory to the seizure of Botha's Pass. That night there was very heavy work getting big naval and other guns up the mountain. On the 8th Botha's Pass was attacked and captured by the 2nd and 11th Brigades, the 10th assisting from Vanwyk. The force moved forward, and on the 11th was fought the battle of Alleman's Nek (see 2nd Queen's). The 10th Brigade, Dorsets leading, attacked and captured the hill on the right of the nek, a very strong position. The advance was admirably made, and the troops engaged were highly praised by General Buller. In his despatch of 19th June (Natal Despatches, p 93) he said, "I was much pleased with their action". Two officers, a colour-sergeant, and a private were mentioned in that despatch, and 5 officers and 2 non-commissioned officers in a later despatch. The battalion's losses were approximately 9 men killed, 2 officers and 53 men wounded.
In Lord Roberts' final despatch 7 officers and 12 non-commissioned officers and men were mentioned.
After the Pretoria-Natal Railway had been occupied the Vth Division was chiefly engaged in marching through and occupying the south-east portion of the Transvaal, acting as garrison at Wakkerstroom and other posts in that district. Their task frequently involved some fighting: the most severe was undoubtedly that which arose from Botha's attempt to reinvade Natal in September 1901. It will be remembered that Major Gough's force of 200 Mounted Infantry was destroyed on the 17th. On the 26th Botha's men attacked Fort Itala (see 2nd Royal Lancaster). The Dorsets were represented there, and on the same day Fort Prospect, which was garrisoned by 35 men of the Dorset Mounted Infantry and 51 of the Durham Artillery Militia under Captain Rowley of the Dorsets, was attacked by 500 Boers. The enemy under cover of a mist got within 20 yards of the sangars held by the militiamen, but they held out and, aided by a maxim, drove off the attack. At all other points the enemy was repulsed after thirteen hours' fighting. Thanks to admirably constructed defences, the losses of the garrison were only 1 killed and 8 wounded. Captain Rowley and his little force were congratulated by General Lyttelton and Lord Kitchener.
Throughout the summer of 1901 the battalion did a lot of heavy marching as the infantry of a column under Brigadier General Bullock which operated chiefly in the south-east of the Transvaal and in the north of the Orange River Colony and between the Delagoa and Natal Railways. Lieutenant Moeller's ' Two Years at the Front' gives a clear and detailed account of the work of that column.
A section from the Dorsetshire Regiment was in the 2nd Battalion Mounted Infantry, and a sketch of the work of their company is given under the Argyll and Sutherland Highlanders.
During the latter phases of the war 2 officers and 8 non-commissioned officers and men were mentioned by Lord Kitchener in despatches for gallant work, and in his final despatch the names of 4 officers and 5 non-commissioned officers and men were added.