Vice Admiral

"Vice Admiral" (中将, Chūjō) is a Marine rank of three star level, equivalent to Lieutenant General in seniority. A Vice Admiral is typically senior to a Rear Admiral and junior to an Admiral.

Vice Admirals in One Piece
The Vice Admiral position is the third highest post in the Marines and currently the one with most representatives seen in the series (before five named Captains) besides common, unnamed grunt soldiers. The highest seen position below a Vice Admiral is that of a Rear Admiral.

Their duties are different from those of common Marine commanders, as is for instance that of commanding 2 out of 10 Buster Call ships. However, one Vice Admiral, John Giant, is seen to have some special authority, as he was the first in the entire Marine Headquarters to receive the report of the Buster Call and could also evidently command other Vice Admirals to dispatch.

The general attire of a Vice Admiral is that of a Marine coat with epaulets and a suit and tie worn below. The only Vice Admiral to wear an attire different from others is, again, John Giant, who wears a gold and red uniform with a strain of medals on his chest.

At least ten of them (John Giant, Momonga, Komir, Onigumo, Doberman, Strawberry, Tsuru, Lacroix, Ronse, and Yamakaji) are known to be stationed in the Marine Headquarters.

Also, it would seem that most Vice Admirals are swordsmen and several have been shown using Rokushiki.

Trivia

 * Many Giants who are shown to be Marines are Vice Admirals, a testament of their immense strength.
 * Many Vice Admirals are swordsmen.