Nigerian troops form the backbone of the peacekeeping force
The bloody civil war in Liberia prompted the Economic Community of West African States (Ecowas) to set up an armed Monitoring Group - Ecomog for short - in 1990.
Nigeria and some other members of Ecowas - a 16-nation group formed in 1975 - were concerned about the war's threat to regional stability. Western countries had already made clear their unwillingness to get involved.
A non-standing military force, Ecomog was made up of soldiers from the national armies of member nations. In practice, regional giant Nigeria contributed most of the troops, materiel and financial backing.
In 2001 the Nigerian president said his country had spent $13bn on peacekeeping operations over 12 years. Hundreds of Nigerian soldiers were thought to have been killed in operations in Liberia and Sierra Leone.
Ecomog soldiers finally left Liberia in 1998, and won recognition for helping to re-establish stability.
Anarchy in Liberia: the catalyst for Ecomog's creation
But there was no respite as neighbouring Sierra Leone slid into a bloody civil war. Ecomog soldiers reinstated deposed President Kabbah and twice drove rebels from the capital before UN forces arrived.
Assessing the Liberia and Sierra Leone operations in 1998, Ecowas ministers decided that Ecomog should form the basis of a regional peacekeeping mechanism.
- 1990 Intervenes in Liberian civil war; presence peaks at 12,000 troops
- 1997 Election of Charles Taylor as Liberian president marks culmination of Liberian mission
- 1997 Deploys large-scale force in Sierra Leone after rebels overthrow President Kabbah
- 1998 Drives rebels from Sierra Leone capital, reinstates Kabbah as president
- 1999 Deploys peacekeepers in Guinea-Bissau after armed conflict between president and rebel military chief
- 1999 Recaptures Sierra Leone capital Freetown after guerrilla offensive
- 2001 Stations troops on Guinea-Liberia border to stop guerrilla infiltration
Ecomog's top brass were answerable to the head of Ecowas. The Ecowas Defence Council was responsible for assessing the situation in a conflict zone and deciding on strategy.
On the ground, Ecomog's force commander oversaw military operations. Before 1999 the force commander did not have complete control of the various contingents, whose leaders also answered to military chiefs in their home countries.
Different political agendas among member states hampered Ecomog's effectiveness. Over Liberia, tensions emerged between states which supported warlord Charles Taylor and those, such as Nigeria, which opposed him.
Nigeria's dominant position within Ecomog led other states to suspect it of using the force to further its own agenda. But other Ecowas nations lacked the resources to undertake significant action without Nigeria.
Ecomog contingents were often poorly-equipped. This reflected the inability of member countries to provide adequate funding for their own militaries.