The following is the experience of the Royal Sussex as found in A Short History of the Royal Sussex Regiment (35th foot – 107th foot), 1701-1926. Printed by Gale & Polden, UK,1927.

1st Batt. arrived in South Africa in January, 1900, reaching the Cape one month later and joining Lord Roberts' army at Bloemfontein in advance on Pretoria. It fought the Boers at the Battle of the Zand River, against formidable defenses.  The Boers were encountered in force at Doornkop, near Johannesburg, and the position was stormed in the face of artillery and rifle fire, the 35th, threatening the enemy's flank, helped in the success of the frontal attack lead by another brigade.  Pretoria was reached on June 5th, and the army marched past Lord Roberts on the Square, the 35th leading the 21st Brigade.  The band bass drum of the 35th was the only big drum in the army which had come through the advance with both heads intact, so it was necessary to pass it from band to band to play the army past Lord Roberts.  Although the heads were intact, the drum had a bullet through the shell from side to side at the Battle of Doornkop while it was lying on the ground with two drummers taking cover behind it, neither of whom were hit.  

The Battle of Diamond Hill followed on June 11 and 12, when the 35th captured an important position and held it under severe shrapnel and rifle fire, 1 officer killed and 1 officer with 16 O/Rs wounded.  Soon after, the 21st Brigade moved south and seized Heidelberg, then onto Reitz and Bethlehem, and took part in the attack on Retief's Nek, July 23rd (1 officer and 3 men KIA, 4 officers and 32 men wounded).  

Lt. General Sir A. Hunter said of the battalion "Your men worked splendidly in the attack.  They could not have done more.  I wish to convey to them my high admiration of the dauntless way they advanced under such fire; nothing could have been finer."  

Retief's Nek was part of the mountain Battle of Wittebergen, in which, after rapid marches and hard fighting, the enemy's forces were surrounded, and an army of over 4,000 men, under Prinsloo, laid down their arms.  The Orange Free State flag of one of the laagers was presented to the Battalion by the General Officer Commanding.  Thereafter the war developed into a guerilla campaign, in which the Battalion took its full share.  

One phase of the services of the 1st Battalion during the South African War calls for special remark, as it was an experience which it is believed fell to no other British infantry unit.  Early in 1901, five companies of the battalion, under Major L.E. du Moulin, were detached as escort to the convoy working from the railway to supply General Bruce Hamilton's mobile column.  With his usual energy, Major du Moulin proceeded to mount his command from the veldt, and by other means of acquisition.  It was not long before he found himself in command of some 300 mounted men who had been taught to ride by the light of bitter experience that it was better to remain on a horse than fall off.  His enterprise was in due course rewarded, for in June, General Hamilton turned Major du Moulin's command into a fighting column, adding a company of Imperial Yeomanry, a section of Royal Field Artillery and a section of Pom Poms.  From this time till the end of the war the column was on trek, seeing almost daily fighting.  The extreme south-east corner was the only part of the Orange River Colony in which it did not operate at some time or another.  

Bt. Lt. Col. du Moulin, D.S.O, was killed in his bivouac on January 27, 1902 whilst gallantly taking part in the successful repulse of a night attack which was made by three Boer commandos upon the bivouac.  Shortly after his death, the column, as such, was broken up, and the mounted men of the Royal Sussex were attached to Col. Hunter Weston's column, and with him took part in the final drive, under General Ian Hamilton, on Vryburg, resulting in the capture of about 500 Boers.  There was nothing spectacular about the fighting, but much hard work was entailed, and many hundreds of miles were covered up and down the Free State and Transvaal chasing the elusive Boer.  Rations were generally scanty; for days, and sometimes for weeks, half or even quarter rations were all that could be issued when away from the railway and water was always scarce.  The extremes of heat and cold were severe, and since tents could not be carried and no houses existed for billets it was a case of the hard ground to lie on with the sky as a roof month after month.  But the climate, on the whole, was healthy, and the Boer was a chivalrous foe.  Peace came at last, after the Battalion had had two and a quarter years of campaigning, during which time it never lost a prisoner.  How many battalions went through the Boer War with such a record?