First Lieutenant (military rank)

Position and insignia

First lieutenants are commonly placed above second lieutenants (or equivalent) and below captains in the officer hierarchy. Insignia differ between nations but often use simple bars, pips, or similar small devices to indicate the grade. In formal rank systems a first lieutenant corresponds to the higher of two lieutenant grades in services that distinguish first and second lieutenants.

Typical duties and responsibilities

Responsibilities assigned to a first lieutenant usually include leadership of small units, staff duties, and serving as deputies to more senior company officers. Typical duties can include:

• Platoon or flight command in combat and training units
• Executive officer or second-in-command at company or battery level
• Specialist staff roles at battalion or wing level
• Mentoring junior officers and managing administrative tasks

Variations, equivalencies and naval use

The rank's place in an international framework is often compared through NATO codes or other equivalency systems, which help translate ranks between armed forces. In some navies and historical contexts the term "lieutenant" or "first lieutenant" refers to a post or appointment—an officer who serves as the ship's executive officer—rather than to a single fixed rank. For general background on the wider lieutenant category see lieutenant.

History and development

The distinction between junior and senior lieutenants grew out of the need to differentiate experience and responsibility among officers with the same basic title. Over time many armies formalized two-grade lieutenant structures to support promotion ladders, career progression and clearer command relationships within small units.

Notable distinctions

Exact privileges, saluting protocols and formal address vary by service. In many countries a first lieutenant will be addressed as "Lieutenant" in conversation, while written forms may include the numeral or full phrase. Care should be taken when comparing ranks internationally, because titles that sound similar can occupy different levels in separate services.

This article summarizes common patterns and variations; practices differ by nation, service, and historical era.