[2] He was promoted to captain on 1 April 1889,[4][6] and in 1891 served as the aide-de-camp to Major General William Elles,[7] commanding the Hazara Expedition of 1891.

[2] He was promoted to major in November 1897,[4][8] and during the Nile Expedition of 1898 he held the post of assistant adjutant general in the Egyptian army, where he was mentioned in despatches and appointed a brevet lieutenant colonel.

[2][9] On returning from Egypt at the start of 1899, Sandbach was appointed as the military secretary to the viceroy of India,[10] a post he held until November,[11] when the outbreak of the Second Boer War meant that he was sent to South Africa.

[4] He worked on the staff in South Africa as assistant adjutant general,[12] for which he was later awarded the Distinguished Service Order (DSO) as well as a second mention in despatches.

[2] In this post, he was given a substantive promotion to colonel in April, following which he spent until October on the half-pay list,[15] whereupon he was made a temporary brigadier general.

[4] In November 1915, Sandbach was appointed to command the 68th (2nd Welsh) Division, a second-line Territorial Force (TF) formation on home defence duties in England.

[23] In February 1917, the 59th Division was ordered to the Western Front, despite concerns that its training schedule had been disrupted by service in Ireland.