Asymmetric warfare
War by proxy: Where asymmetric warfare is carried out (generally covertly) by allegedly non-governmental actors who are connected to or sympathetic to a particular nation's (the "state actor's") interest, it may be deemed war by proxy. This is typically done to give the state actor deniability. The deniability can be crucial to keep the state actor from being tainted by the actions, to allow the state actor to negotiate in apparent good faith by claiming they are not responsible for the actions of parties who are merely sympathizers, or to avoid being accused of belligerent actions or war crimes. If proof emerges of the true extent of the state actor's involvement, this strategy can backfire; for example, see Iran-contra and Philip Agee.

Examples: 

American Indian Wars: Benjamin Church designed his force primarily to emulate Native American patterns of war. Toward this end, Church endeavored to learn to fight like Native Americans from Native Americans. Americans became rangers exclusively under the tutelage of the Native American allies. (Until the end of the colonial period, rangers depended on Native Americans as both allies and teachers.)
Church developed a special full-time unit mixing white colonists selected for frontier skills with friendly Native Americans to carry out offensive strikes against hostile Native Americans in terrain where normal militia units were ineffective. Church paid special care to outfitting, supplying and instructing his troops in ways inspired by indigenous methods of warfare and ways of living. He emphasized the adoption of indigenous techniques, which prioritized small, mobile and flexible units which used the countryside for cover, in lieu of massed frontal assaults by large formations. Benjamin Church is sometimes referred to as the father of Unconventional warfare.

American Revolutionary War: From its initiation, the American Revolutionary War was, necessarily, a showcase for asymmetric techniques. In the 1920s, Harold Murdock of Boston attempted to solve the puzzle of the first shots fired on Lexington Green and came to the suspicion that the few score militiamen who gathered before sunrise to await the arrival of hundreds of well-prepared British soldiers were sent to provoke an incident which could be used for Patriot propaganda purposes. The return of the British force to Boston following the search operations at Concord was subject to constant skirmishing by Patriot forces gathered from communities all along the route, making maximum use of the terrain (particularly, trees and stone field walls) to overcome the limitations of their weapons – muskets with an effective range of only about 50–70 meters. Throughout the war, skirmishing tactics against British troops on the move continued to be a key factor in the Patriots' success; particularly in the Western theater of the American Revolutionary War.
Another feature of the long march from Concord was the urban warfare technique of using buildings along the route as additional cover for snipers. When revolutionary forces forced their way into Norfolk, Virginia and used waterfront buildings as cover for shots at British vessels out in the river, the response of destruction of those buildings was ingeniously used to the advantage of the rebels, who encouraged the spread of fire throughout the largely Loyalist town and spread propaganda blaming it on the British. Shortly afterwards, they destroyed the remaining houses because they might provide cover for British soldiers.
The rebels also adopted a form of asymmetric sea warfare by using small, fast vessels to avoid the Royal Navy and capturing or sinking large numbers of merchant ships; however the Crown responded by issuing letters of marque permitting private armed vessels to undertake similar attacks on Patriot shipping. John Paul Jones became notorious in Britain for his expedition from France in the sloop of war Ranger in April 1778, during which, in addition to his attacks on merchant shipping, he made two landings on British soil. The effect of these raids, particularly when coupled with his capture of the Royal Navy's HMS Drake – the first such success in British waters, but not Jones' last – was to force the British government to increase resources for coastal defense, and to create a climate of fear among the British public which was subsequently fed by press reports of his preparations for the 1779 Bonhomme Richard mission.
From 1776, the conflict turned increasingly into a proxy war on behalf of France, following a strategy proposed in the 1760s but initially resisted by the idealistic young King Louis XVI, who came to the throne at the age of 19 a few months before Lexington. France ultimately drove Great Britain to the brink of defeat by entering the war(s) directly on several fronts throughout the world.

American Civil War: The American Civil War saw the rise of asymmetric warfare in the Border States, and in particular on the US Western Territorial Border after the Kansas-Nebraska Act of 1854 opened the territories to vote on the expansion of slavery beyond the Missouri Compromise lines. Political implications of this broken 1820's compromise were nothing less than the potential expansion of slavery all across the North American continent, including the northern reaches of the annexed Mexican territories to California and Oregon. So the stakes were high, and it caused a flood of immigration to the border: some to grab land and expand slavery west, others to grab land and vote down the expansion of slavery. The pro-slavery land grabbers began asymmetric, violent attacks against the more pacifist abolitionists who had settled Lawrence and other territorial towns to suppress slavery. John Brown, the abolitionist, travelled to Osawatomie in the Kansas Territory expressly to foment retaliatory attacks back against the pro-slavery guerrillas who, by 1858, had twice ransacked both Lawrence and Osawatomie (where one of Brown's sons was shot dead).
The abolitionists would not return the attacks and Brown theorized that a violent spark set off on "the Border" would be a way to finally ignite his long hoped-for slave rebellion. Brown had broad-sworded slave owners at Potawatomi Creek, so the bloody civilian violence was initially symmetrical; however, once the American Civil War ignited in 1861, and when the state of Missouri voted overwhelmingly not to secede from the Union, the pro-slavers on the MO-KS border were driven either south to Arkansas and Texas, or underground—where they became guerrilla fighters and "Bushwhackers" living in the bushy ravines throughout northwest Missouri across the (now) state line from Kansas. The bloody "Border War" lasted all during the Civil War (and long after with guerrilla partisans like the James brothers cynically robbing and murdering, aided and abetted by lingering lost causers). Tragically the Western Border War was an asymmetric war: pro-slavery guerrillas and paramilitary partisans on the pro-Confederate side attacked pro-Union townspeople and commissioned Union military units, with the Union army trying to keep both in check: blocking Kansans and pro-Union Missourians from organizing militarily against the marauding Bushwhackers.
The worst act of domestic terror in U.S. history came in August 1863 when paramilitary guerrillas amassed 350 strong and rode all night 50 miles across eastern Kansas to the abolitionist stronghold of Lawrence (a political target) and destroyed the town, gunning down 150 civilians. The Confederate officer whose company had joined Quantrill's Raiders that day witnessed the civilian slaughter and forbade his soldiers from participating in the carnage. The commissioned officer refused to participate in Quantrill's asymmetric warfare on civilians.

Philippine–American War: The Philippine–American War (1899–1902) was an armed conflict between the United States and Filipino revolutionaries. Estimates of the Filipino forces vary between 100,000 and 1,000,000, with tens of thousands of auxiliaries. Lack of weapons and ammunition was a significant impediment to the Filipinos, so most of the forces were only armed with bolo knives, bows and arrows, spears and other primitive weapons that, in practice, proved vastly inferior to U.S. firepower.

The goal, or end-state, sought by the First Philippine Republic was a sovereign, independent, socially stable Philippines led by the ilustrado (intellectual) oligarchy. Local chieftains, landowners, and businessmen were the principales who controlled local politics. The war was strongest when illustrados, principales, and peasants were unified in opposition to annexation. The peasants, who provided the bulk of guerrilla forces, had interests different from their illustrado leaders and the principales of their villages. Coupled with the ethnic and geographic fragmentation, unity was a daunting task. The challenge for Aguinaldo and his generals was to sustain unified Filipino public opposition; this was the revolutionaries' strategic centre of gravity. The Filipino operational center of gravity was the ability to sustain its force of 100,000 irregulars in the field. The Filipino General Francisco Macabulos described the Filipinos' war aim as "not to vanquish the U.S. Army but to inflict on them constant losses." They initially sought to use conventional tactics and an increasing toll of U.S. casualties to contribute to McKinley's defeat in the 1900 presidential election. Their hope was that as president the avowedly anti-imperialist future Secretary of state William Jennings Bryan would withdraw from the Philippines. They pursued this short-term goal with guerrilla tactics better suited to a protracted struggle. While targeting McKinley motivated the revolutionaries in the short term, his victory demoralized them and convinced many undecided Filipinos that the United States would not depart precipitously. For most of 1899, the revolutionary leadership had viewed guerrilla warfare strategically only as a tactical option of final recourse, not as a means of operation which better suited their disadvantaged situation.