John Cameron was Master from the first voyage of 1900. (What date was the maiden voyage please?)Haddock took command from ?1907? and Henry Smith from late 1912. Sorry, can't as yet give you the precise dates but I'll find them if you need them.
6 September 1899: Oceanic II, commanded by Capt. J. G. Cameron, begins
her maiden voyage, Liverpool-Queenstown-New York. Carrying 1,456
passengers and a crew of 434, Oceanic will arrive in New York on 13
September. (Sources: The New York Times, 14 September 1899; Bonsor's
North Atlantic Seaway; Haws' Merchant Fleets.)