The Native Americans were of absolute importance to whichever side they joined during the colonial and post-revolutionary America. The indigenous people assisted in teaching the European American how to fight with hit and run tactics, more suitable to the American continent as well as how to plant and gather food in a manner that suited the land. During wars, such as the French-Indian War or the Revolutionary War, the American Indians were drafted to assist both sides of the wars for added numbers, learning new strategies of warfare as well as the layout of the land as applicable to army management and battle field warfare.
The early studies of the colonial American warfare suggested that though the Native Americans did take part in the wars, and did contribute to a new American way of warfare, however, they lacked to acknowledge how much of an influence Native American warfare had on the development of warfare on the American Continent. “More often European military institutions (…) proved to be insufficiently flexible to meet the challenges of the frontier”.
The book “European and Native American Warfare” by Starkey Armstrong brings to light the presence and effect the Native Americans had on how warfare took its path, noting that in the states of Massachusetts, Connecticut and Virginia, where the militia was more present and effective, was also where there was the most involvement of recruiters (European Americans) and recruited (Native Americans).
Most of the assumptions that Native American warfare contributed little or not at all, are due primarily to the descriptions of the earliest European explorers, being unfamiliar with how it took place, and unfamiliar with the quick tactics being used. It is only when others, less involved in the warfare themselves, take to investigating the warfare methodologies of the Natives that we are brought to the knowledge that it was not a ritualistic mass murder for no other reason than to “obtain manhood” or social status, but rather, raids out of necessity, with a general rule of only happening when out of necessity, also, without any record of any single catastrophic attack resulting in the death of most or all of a community. This confirms that they were aware of their own strategies, whether as well developed or not is beyond the point, and not simply acting on an animalistic impulse to kill, and can, be considered of real use to any willing to learn said strategies. 
Native American warfare is still considered crude, as they lacked infrastructure in their attacks or defenses, but be that as it may, it proved key in the European American warfare. The Natives had developed hit and run as well as ambush tactics to make up for their lack of structured attacks, as without this element, their internal warfare came down to attrition and the only relevant factor were numbers, causing large losses on either side. Not all European Americans did adopt these strategies, but any that did not adapt to them, had to react to them at the same level, being the difference between extreme loss and overwhelming victory, as evidenced by the militia in the French-Canadian war. 
The British are known as the primary user of Native’s numbers and help in their colonial conquests. This is evidenced by the numbers of some troops during their conquest of the Gaels in Ireland as well as the Native American Indians in America. The natives were used for counterinsurgency or as simple numbers when numbers were all that was necessary to intimidate the opponent. The colonists did have more experience with handling the division of power present in the native culture, taking advantage of it by using internal rivalries to add to their own forces, or by indirectly favoring one village with the expectation of help in close battles.
Colonists managed to succeed in various crucial situations simple by the help of the numbers of the Native Americans, as evidenced by the Massacre of Pequots at Mystic (Connecticut) in 1637, where 90 Englishmen managed the victory backed by hundreds of Narragansetts and Mohegans. Not only did these added numbers cause the victory, but in contrast, whenever the natives refused, which they often did if they felt the number of European American troops was not sufficient, English forces would not only not manage to take the victory, but would have to abandon the campaign altogether.
Lastly, the Native Americans knowledge of the land was decisive in some battles, knowing the land, its hardships, shortcuts and where enemy troops would likely be placed is something only natives can know for certain, having been raised in the land. To exemplify, the Spanish were successful against the Incas and Aztecs with their armored horses, however, during battles taking place in Florida, where they were unfamiliar with the Swamps, they were no match to the Native American warfare, especially when combined with that of the European American as well.
In conclusion, the Native Americans did indeed matter, to a great amount, in the warfare of the European American, and that can even be extended to say that without the indigenous people of the Americas, the European American would not have had a nearly as successful entry to the land, likely failing to get by during times of scarce food, or during any wars where the opposite side had the help of the Native Americans.
 Starkey Armstrong. “European and Native American Warfare” (London: UCL Press, 1998), 15.
 Wayne E. Lee, “Early American Ways of War: A New Reconnaissance”, Historical Journal 44, no. 1 (March 2001): 270.
 Ibid, 273.
 Ibid, 274.
 Wayne E. Lee, “Using the Natives against the Natives: Indigenes as ‘Counterinsurgents’ in the British Atlantic, 1500-1800”, Defense Studies 10, no. ½ (March 2010): 91.
 Alan Gallay, “The Indian Slave Trade the Rise of the English Empire in the American South, 1670–1717” (New Haven, CT: Yale UP, 2002): 84
 Wayne E. Lee, 91.
 Raymond Wilson, “Native American and European encounters in North America”, Journal Of American Ethnic History 16, no. 4 (Summer 1197): 89