In military mess etiquette, which way is the port passed at dinner?

Decanters of port wine are placed in front of the ranking guest and at several other points around the table. Each officer fills his own glass with port wine. This custom derives from the earliest days, when it was usual for him who would drink to another to fill his own horn. Thus the toast, from the first moment is a completely spontaneous gesture.

As each diner fills his own glass, he passes the decanter from left to right. The decanters are not passed by the waiters. This procedure continues with the port moving around the table counter-clockwise until all glasses are charged. When passing port, the decanter must never rest on the table until the last glass at the individual table is charged, and that each glass is charged whether the member drinks or not. When a decanter has reached the end of the table and the last glass is charged, it may be set down. Decanters should not accumulate in front of one officer. It is incorrect for the port to change direction, so if an officer refuses the decanter on a given round, he must wait until the next round is commenced. He may however, pass his glass down to an officer who has a decanter at the moment, although this is not considered to be good form. No one drinks the port until the first toast is proposed.