(British) Army List - 1 April 1857

Page 246 notes Conway Richard REEVES as a Lieutenant with the 2nd Battery Royal Artillery.

He was promoted on Lieutenant on 20 December 1856.

Page 375, summarising the recent Promotions, Appointments &c, notes Gentleman Cadet C. R. Reeves is appointed Lieutenant in the Royal Artillery effective 20 Dec 1856

Source

(British) Army List - for 1857, page 246 & page 375.