Corvette Lieutenant is a rank in some navies, especially those of Spain and Latin America, roughly equivalent to a Royal Navy Acting Sub-Lieutenant or a US Navy Ensign. The French Navy equivalent is a Ship of the Line Ensign (2nd Class). The Royal Navy of the United Kingdom is the oldest of the British armed services (and is therefore the Senior Service). ... A Sub-Lieutenant is a junior naval commissioned officer, ranking below a Lieutenant. ... The United States Navy (USN) is the branch of the United States armed forces responsible for naval operations. ... Ensign is a junior rank of commissioned officer in the militaries of some countries, normally in the infantry or navy. ... The French Navy, officially called the National Navy (French: Marine Nationale) is the maritime arm of the French military. ... Ensign is a junior rank of commissioned officer in the militaries of some countries, normally in the infantry or navy. ...