What is battalion strength?

A battalion is a unit of military organization. It has no fixed universal definition as to the size or composition of it. However, it falls in the organizational hierarchy between a company and a regiment/brigade. That is, it is larger than a company (and, is usually composed of at least two companies, plus other elements), but smaller than a regiment or brigade (which may consist of several battalions).

In general, the company or equivalent unit is the smallest "managed" combat element of an army - that is, the company is the smallest organization which has a dedicated command section that does not immediately engage in combat. (Platoons and smaller units have command sections, but command is in many ways secondary to these units' combat requirements). In a company, the command section may incidentally engage in combat (as they are in close proximity to the front), but their main function is command and control. In most militaries, companies are commanded by a captain or equivalent rank.

Battalions are made up of several companies, and generally are the first unit to have significant heterogeneous makeup (that is, they have several different units which have significantly different equipment and missions). For example, a typical infantry battalion will have several infantry companies (made up of soldiers equipped with light firearms), but it will likely also have several subunits for logistical supply (such as a truck section) and perhaps heavy fire support (a section of mortars or light artillery). Battalions are the first place where the concept of "combined arms" starts to show up. Battalions tend to be commanded by a major, or more rarely, a lieutenant colonel.