The term ultimately goes back to Late Latin capitaneus meaning "head of [something]"; in Middle English adopted as capitayn in the 14th century, from Old French capitaine.
The funding to provide for the troops did not come from the monarch or their government; the captain responsible for feeding, housing, and provisioning their company.
Today, a captain is typically either the commander or second-in-command of a company or artillery battery (or United States Army cavalry troop or Commonwealth squadron).
In the U.S. Army, lawyers who are not already officers at captain rank or above enter as lieutenants during training, and are promoted to the rank of captain after completion of their training if they are in the active component, or after a certain amount of time, usually one year from their date of commission as a lieutenant, for the reserve components.
However, like their Commonwealth counterparts, rank braids are pearl grey and increase in half strip increments.