The 4th Hussars and the 5th PLDG were not mobilized in the First World War, but they both contributed volunteers to and aided in the recruiting of the 8th Regiment, Canadian Mounted Rifles.

The squadron was again expanded into a regiment in 1903 as the 5th 'Princess Louise Dragoon Guards'. During the Second Boer War, volunteers from the squadron fought with the Imperial forces in South Africa. Meanwhile, in Ottawa, the city's independent cavalry troop (formed in 1872) came under the patronage of the Princess Louise, Marchioness of Lorne, during her time there as vice-regal consort (1878–80), and the troop was expanded to an independent squadron named The Princess Louise Dragoon Guards. In 1932, they were again Redesignated as the 4th Hussars of Canada. This regiment adopted hussar uniforms (with buff facings ) and hussar customs in 1893, being Redesignated as the 4th Hussars. Four of these troops (in Kingston, Napanee, Loughborough and Picton) were united under a regimental headquarters in 1875, becoming the 4th Provisional Regiment of Cavalry. Several independent troops of cavalry in the Province of Canada's volunteer militia were formed in the Kingston area starting in 1855. 4.1 4th Princess Louise Dragoon Guards (15 December 1936).

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