units were light infantry battalions and independent companies designated . These battalions and companies were designed to operate autonomously and isolated, without much support from the higher echelons, so having a strong service support component. They were deployed in a grid system () along the theatre of operations, with each one being responsible for a given area of responsibility. Usually, a regiment-sized (battlegroup) commanded a sector, with this being divided in several sub-sectors, each constituting the area of responsibility of a battalion. Each battalion, in turn, had its field companies dispersed by the sub-sector, each with part of it as its area of responsibility. From 1962, four intervention zones (Northern, Central, Southern and Eastern) were established – renamed "military zones" in 1967 – each grouping several sectors. Due to the low scale guerrilla nature of the conflict, the company became the main tactical unit, with the standard organization in three rifle and one support platoons, being replaced by one based in four identical sub-units known as "combat groups". The Army also fielded regular units of artillery, armored reconnaissance, engineering, communications, signal intelligence, military police and service support. Besides the regular units, the Army also fielded units of special forces. Initially, these consisted of companies of , trained for guerrilla and counter-insurgency warfare. The Army tried to extend the training of the special to all the light infantry units, so disbanding those companies in 1962. These proved, however, impracticable and soon other special forces were raised again in the form of the Commandos. The Commandos and a few specially selected units were not deployed in grid, but served instead as mobile intervention units under the direct control of the higher echelons of command. An unconventional force also fielded by Army was the Dragoons of Angola, a special counterinsurgency horse unit raised in the middle 1960s. The Portuguese Navy forces were under the command of the Naval Command of Angola. These forces included the Zaire Flotilla (with patrol boats and landing craft operating in the river Zaire), naval assets (including frigates and corvettes deployed to Angola in rotation), Marines companies and Special Marines detachments. While the Marines companies served as regular naval infantry with the role of protecting the Navy's installations and vessels, the Special Marines were special forces, serving as mobile intervention units, specialized in amphibious assaults. The initial focus of the Navy was mainly the river Zaire, with the mission