Acting (rank)

An Acting rank, is a military designation allowing an commissioned- or non-commissioned officer to assume a rank—usually higher and usually temporary—with the pay and allowances appropriate to that grade. As such, an officer may be ordered back to the previous grade. This situation may arise when a lower-ranking officer is called upon to replace a senior officer, or fill a position higher than the current rank held.

Addressing
When addressing an individual with an acting rank, the person should be addressed as if the full rank was held. For example, a member who is an acting master seaman would be addressed as "Master Seaman Smith", and not "Acting Master Seaman Smith" since the "acting" is a designation, regardless of the individual's actual rank and clerical designation. It should also be noted that an exception is the rank of acting sub-lieutenant: they should be addressed verbally as mentioned ("sub lieutenant), but in written documents should have their full, unedited title of "acting sub lieutenant."

United States Navy
In the United States Navy, acting appointments were common during the 19th century. The number of commissioned naval officers at each rank in the Navy was fixed by Congress, so it was difficult to fill vacancies if the number of ships exceeded the number of officers needed to man those ships. Acting appointments were also common with warrant officers and ratings, although neither were subject to congressional approval and were simply temporary assignments.

The regulations stated that in the United States, acting appointments were not allowed unless specifically authorized by the Department of the Navy. In most other cases, only the Commander-in-Chief of a fleet or squadron would be authorized to appoint an officer to fill a vacancy, and this order would be subject to approval of the Department of the Navy. In this way, the Department of the Navy was able to fill vacancies while the Navy grew before Congress took action to permanently increase the number of officers. Outside of the United States and not part of a fleet or squadron, the commanding officer of the ship was allowed to appoint officers to a higher rank in the case of death on board the ship.

The officer was temporarily appointed to the higher rank, appended acting to his new rank, wore the uniform of the higher rank, and was addressed and paid at the higher rank. When the ship returned to the United States, or joined a fleet or squadron, the appointment was subject to review by the commander-in-chief of the fleet or squadron or the Department of the Navy.

Another type of temporary appointment was an order to perform. This was issued in a similar manner to an acting appointment for a lower grade officer to perform the duties of a higher grade officer, except that their pay, rank and uniform remained at the lower grade.

Similar to the many brevet ranks in the Union Army, acting appointments were extremely common during the American Civil War. Congress authorized the Department of the Navy to purchase vessels and appoint acting or volunteer officers to man them until the end of the conflict. By the end of the War, most officers were appointed to a higher acting rank, and their appointments lasted until the end of the war at which point many were discharged from the Navy.