Expeditionary Forces

The Expeditionary Forces form the bulk of the SFMC, providing direct ground combat capability when needed, insurrection and riot control where anticipated and site security of Star Fleet (and UFP) assets outside of UFP territory. (They may also be called in to work alongside Star Fleet Security within the UFP, as called upon.) The commanders of an expeditionary force report directly to the Commandant of the Star Fleet Marine Corps, so there is no Expeditionary headquarters element between them.

An expeditionary force will be comprised of up two Marine divisions, but oftentimes much smaller sizes, as the situation demands. Similarly, if the situation requires a significant development of the Corps, any (or all) force(s) may easily control many divisions, in order to accomplish the requirements of whatever front on which they are responsible. In peacetime, a force may be located on a sector capital, but its component divisions located on other planets (usually within the same or neighboring sectors).

Expeditionary Forces are commanded by a Lieutenant General, with a Major General as the executive officer.

An Expeditionary Force (Echelon III) is broken down into the following hierarchy:

Marine Division (Echelon IV): a Marine division is comprised of 2 Marine brigades (18,000 Marines, 120 tanks, 480 tank troops, 1,200 Seabees), 2 mechanized battalions (120 IFVs, 360 mechanized crew), 1 artillery battalion (5 batteries of 6 guns each, 150 total artillery crew) and may be separated between member planets within a sector, or co-located on the same planet (usually, in this case, the sector capital). They are commanded by Major Generals.
- Marine Brigade (Echelon V): a Marine brigade is comprised of 3 Marine regiments (9,000 Marines), plus 1 armor battalion (60 tanks, 240 troops) and 1 combat engineer battalion (600 Seabees), often co-located on the same garrison planet, but separated (when possible) around it's surface at differing camps. Each brigade is command by a Brigadier General.
  - Marine Regiment (Echelon VI): a Marine regiment is comprised of 3 infantry battalions of 1,000 Marines each and is intended to be the smallest deployed unit to a war zone/planet. However, they may be deployed in battalion strength (or even smaller units), if the situation does not warrant (or even prevents) larger deployments. Regiments are garrisoned as a unit within one camp, or a series of co-located camps and are commanded by a Colonel.

An expeditionary force will also be assigned an air combat element of an appropriate size, deployed by Aerospace Operations, and usually comprised of a mobility unit commensurate to the size of the force, plus a fighter unit (usually from the Air Combat Branch). The element may be reduced in size once assault landings are completed, though a component is usually provided to allow sufficient planetary mobility and air coverage.

While Marine units may have informal names (after their garrison planets, symbolic terms and totems or battles), their official names are regimented and logical. Expeditionary Forces are numbered sequentially in single digits (ex: 1st Expeditionary Force). Marine Divisions are are numbered with 2 digits, also sequentially, starting with the 10th Marine Division. As whole divisions are moved between forces, their subordinate commands will not change and are numbered according to their parent division. Marine Brigades are numbered with 3 digits, the first 2 comprised of their division's number (ex: 101st Marine Brigade), while Marine Regiments are numbered with 4 digits, the first 3 comprised of their brigade (ex: 1011th Marine Regiment). Battalions assume the name of their regiment, followed by a Greek letter (alpha, beta, gamma) designation (ex: 1011th Alpha Battalion).

Expeditionary Force commanders, all subordinate flag officers and colonels are named NPCs.