Insurgent

The Iraqi insurgency is composed of a diverse mix of militias, foreign fighters, all-Iraqi units or mixtures using violent measures against the United States-led multinational force in Iraq in Iraq and the post-2003 Iraqi government, or by propaganda or money supportive thereof. The fighting appears both as armed conflict with the United States-led military coalition, as well as sectarian violence among the different ethnic groups within the population. The insurgents are involved in asymmetric warfare and a war of attrition against the US-supported Iraqi government and US forces, while conducting coercive tactics against rivals or other militias.

http://en.wikipedia.org/wiki/Iraqi_insurgency

My example: The American Revolution was fought by insurgent colonists against the British Redcoats.