If a Navy Rear Admiral and an Army Major General hold their commissions from the same date, who is considered to be the senior officer?

elburcher

That would depend on the command(unit, etc.)to which they were assigned. There is "positional authority" in which case the the one whom has been placed in-charge via Job Description(such as Commanding Officer and Executive Officer) is the senior regardless of date of rank. That is the position of Commanding Officer is obviously senior to his Executive Officer, so, all other thing being equal, the one appointed Commanding Officer is Senior. Line Numbers Once selected for promotion by the promotion board, not all officers are promoted at the same time. Instead, officers are assigned a "line number." Each month, the service releases the line numbers of officers to be promoted during the month. This ensures a smooth promotion flow throughout the year following the promotion board. Line numbers are determined using the following criteria: * Date of Rank in their current grade * Date of Rank in their previous grade * Total Active Federal Commissioned Service Date * Total Federal Commissioned Service Date (which would include Guard/Reserve time) * Regular Officer over Reserve Officer * Date of Birth * Reverse social security number, with the lowest number taking precedence http://usmilitary.about.com/od/promotions/l/blofficerprom.htm May 28 08, 7:37 PM