Captain J.A. Lawson was one of the original Officers of the notorious Steineacker's Horse. Along with Major F. Von Steinaecker, a small and pugnacious former Prussian Officer, he served in the ranks of the Colonial Scouts in Natal and took part in the famous raid to Komati Poort:
'The Colonial Scouts were disbanded in March 1900, and in that month Steinaecker, now a Lieutenant, selected six men, of whom Scouts Duncan, Lawson, Gray and Carmichael served with him for many months, Lawson finishing as Captain, and being present at the disbandment of the corps in February 1903. With this small party Steinaecker left Etshowe on 3rd April 1900, and rode or walked through Zululand and Swaziland, a distance of 500 miles. Their horses having died of horse-sickness, the party were on foot when the Transvaal border was reached ... The party intended to attempt the blowing up of the great bridge at Komati Poort, but found it too strongly guarded. Steinaecker and three men now struck through the bush, swam the Komati River 'when the crocodiles were off their feed', travelled all the night of the 16th June, and on the 17th, after dark, placed nearly 100lb. of dynamite between the masonry and girders off a bridge at Malelane, forty miles up the line, and destroyed it. The fact that the Boers afterward restored the bridge does not detract from the credit due to Steinaecker and his gallant men for their splendid piece of daring, which, strangely enough was never recognised in despatches.'
Steinaecker's Horse was officially raised in October 1900 and won a fearsome reputation on the Portugese Border. It operated in the area which is now the Kruger National Park and, as well as Boers and restless natives, was exposed to the dangers of lions, crocodiles and malarial swamps. Under the quixotic leadership of Steinaecker, it fought as a self contained unit and was responsible for a large number of captures of Boers and cattle. So good was it that it remained in the Northern Transvaal and on the border until it was replaced by the S.A.C. in February 1903. Steinaecker's Horse was viewed with some dismay by several Regular Officers who were convinced that a large trade in cattle-rustling and other nefarious activities were being perpetuated and this view was not dispelled by several colourful episodes, not least of which was that of the party of men who turned up in Barberton with an unexplained safe full of money in 1902.