In March 1836 he was appointed Assistant Surgeon, 17th Light Dragoons, replacing Assistant Surgeon Henry Goffe Parken (author of Dissertatio medica inauguralis de neuralgia, 1820), who was put on half-pay.
After various duties in Malta, he was, in 1844, appointed surgeon to the 17th Lancers (which is now famous for its participation in the Charge of the Light Brigade).
In 1854 Gibson was put under the command of the British expeditionary force under the leadership of FitzRoy Somerset, 1st Baron Raglan.
On 19 May of 1854, Gibson landed at the Kulali Barracks[1] in the environs of Istanbul (called by the British Constantinople).
After the Duke's health had reached a sufficient stage of recovery, Gibson accepted, on 1 May, a promotion, approved by Director General Army Medical Department Andrew Smith, to Deputy Inspector General.
[1] On 1 June 1855 Gibson arrived in Malta, where he became officer in charge of the Convalescent Hospital for invalids from the Crimea at Fort Chambray on the island of Gozo.
There he was appointed Deputy Inspector of Hospitals, as well as Principal Medical Officer (PMO) Aldershot.
Whilst in England in 1857, he was made Companion of the Order of the Bath (CB) in recognition of his services in Crimea.
[1] Gibson's administration of the Army Medical Department was considered by some "disastrous"[1] or "rotten in the management".
[8] However, Warren Webster, in charge of Dale General Hospital in 1865, argued that Director General Gibson and his immediate subordinate the Inspector General should not be held responsible "for things left undone when their requisitions for supplies and laborers were cast aside unnoticed and unfilled" — even though there was undoubtedly "defective drainage, untrapped sewerage, nearness of an over-charged graveyard, presence of all kinds of filth and imperfect ventilation at the hospitals at the hospitals of Scutari and Kulali".