the information is not added to the project, the project exists for members who are interested in a certain topic and are willing to dedicate time to it ;>
Ideally, you would have the information in the person's profile, and we can add profile to a category, or create new categories if appropriate, based on that info.
the primary purpose of adding a ship category is to have a place that all of the people assigned to the ship can be listed, this is the same thing we are trying to accomplish by adding people to units such as Division, Regiment, etc.
Some ships exist to transport troops, so for a fairly short period of time, an Army or Marine unit would be on board while in transit, but not really assigned/part of the ship. In these cases, you could add a reference to the ship [[:Category:xxx]] instead of adding to the ship [[Category:xxx]]. There are also cases such as Marines assigned to a ship as part of its crew, they would be added to the ship.
General Patton was in command of several units throughout the war. If you do not have an actual unit, if you had a date period/location, we could check that against General Patton's record and at least determine the upper level command that your Uncle could be placed in, such as 1943 Sicily 7th Army, 1944 France 3rd Army, 1945 Germany 15th Army. From that point, additional research might be able to narrow his service unit down to a specific Division or Regiment.