The greatest violence in human history has happened because of the colonisation drive that several of the resurgent European powers, devoid of any ethical considerations, initiated to grab whatever they could in the rest of the world. It began with the coming of the Age of Discovery. Initially in the closing decade of the 15th century it was marked by Portuguese and Spanish exploration of the New World (Americas), the coasts of Africa, the Middle East, India and East Asia making them global empires in turns. Subsequently during 16th, 17th and 18th centuries England, France, the Dutch Republic and Tsarist Russia also joined this race of exploration and expansion leading them to establish their own empires. Therefore, the European quest to secure colonies led to colonial wars among the aspiring colonial powers like Spain, Portuguese, Britain, France, Dutch and Russia in different parts of the world. Within India itself a number of such wars were fought among French, Portuguese, Dutch and British till Britain finally neutralised the rest and established almost a complete control over the sub-continent and its peripheries. In a way World War 1 & 2 were culmination of colonial wars among the established and aspiring colonial powers (like Italy, Germany and Japan) that brought so much of destruction (mainly) in Europe that considerably weakened all these thereby contributing, as a vital factor, in the decolonisation process.
Colonialism did violence in places that it occupied. This violence had political, economic, social, cultural, physical and environmental dimensions and consequences. In the context of newly discovered continents like Americas and Australia it decimated almost whole populations of aboriginals (natives), replacing them with Europeans on their lands. It dislocated the whole populations from parts of Africa putting them in the service of white masters as slaves. These were used to exploit and extract wealth from lands that the colonisers occupied. It left a terrible legacy of violence for colonies to deal with even after their independence. Colonialism also contributed to wars resulting from the resistance that prospective colonies offered to the colonising process. In India there were a series of such battles and wars. The significant among these were, the Battle of Plassey (1757) with which the British East India company took over the control of the rich province of Bengal establishing foothold to press further in India, and First War of Independence (1857) the victory in which established the complete sway of the British imperial control over whole of India. In between there were a large number of violent campaigns that British got into with the resisting rulers in different parts of the country. The violent conflicts also happened because of the various civil groups offering resistance at their level as well.
After establishment of colonialism a new wave of anti-colonial struggles followed (wiser from their previous experiences of the failures of the violent resistances) mostly in civil, political and non-violent way. There were violent segments of anti-colonial struggles like INA in India. But along with these, more important factor that prompted decolonisation was the self destructive war (WW. II) that brought considerable destruction in Europe and undermined the capacity of conventional colonial powers to hold on to their colonies any further. In the history of colonialism only instance where mainly a violent resistance pushed out a powerful colonial power with its own indigenous resources was the American War of Independence (1776-83) which resulted in the formation of the United States of America. The success of the struggle was more because the people on both sides by and large were of same origin, had similar social, cultural and educational background and operated with comparable strategy, technology and weaponry. In this the Americans had advantage of operating within a favourable geo-social context and enjoyed a number of other operational, tactical, geo-physical advantages that played important role in their success.
Colonialism created its own contentious legacy for decolonised countries to grapple with. Colonial powers were insensitive to historically recognised natural borders in colonies in ethno-cultural and geographical terms. Its border management was subordinate to its own interests and conveniences. Thereby it disturbed ethnic balances, undermined development processes, creating economic distortions, submerged regions and divided many for its own convenience and interests. Thus borders got erected somewhat arbitrarily with little regard to the geo-physical feasibility, composition of people and their historical placement in terms of cultural connectivity, communication and economic linkages etc. Because of this a number of countries were artificially divided and created that had “little relationship with the socio-cultural make-up of the people and their history”. In the process a number of new issues of contention got created. For example border problem between India and China, India and Pakistan (now Bangladesh), Pakistan and Afghanistan, Sri Lankan Tamil issue, the problems in the Northeast of India, Palestinian issue, Arab fragmentation, along with many other problems have been born out of the colonial legacy. Ethnic imbalances and divides, issues of communalism, apartheid and slavery were also the legacy of colonialism that created violent internal strife within several postcolonial states.
While some of these problems stand addressed by now there are many that continue to be contentious afflicting several of the post colonial states with a number of violent conflicts. Some conflicts like border issues between India & China after 1962 war has remained dormant allowing uneasy peace between the two countries. Some issues like the Tamil problem in Sri Lanka under the stronger state might that defeated the LTTE has been only pushed under carpet but not addressed with the objective of resolving the issue. Most chronic of these unresolved issues that resulted in a number of wars and continued internal strifes constantly threaten peace in their respective regions. There are a few cases where, at the face of it, violent resistance seem to have succeeded in defeating colonial/hegemonic powers. But in their case it was a combination of factors that brought the change. During hey days of sweeping decolonisation process French lacked legitimacy to hold on to Algeria beyond a point against the violent anti-colonial uprising. In such and some other cases the occupying powers had even internal domestic factors that added pressure for their withdrawal from their former colonies.
In addition, to conflicts created by the colonial legacy, global peace in the post World War II period was undermined by the cold war between the former Soviet Union & the United States. Because of their mutual nuclear deterrence they did not go for any direct violent engagement with each other. But they tried to undermine each other through a number of proxy conflicts like in the Koreas (1950-1953) Vietnam, (1955-1975) & Afghanistan (1978-1989), just to mention a few. Most of these conflicts ended in a stalemate forcing aggressive power to an un-ceremonial retreat but leaving behind very bad legacy as in the case of Koreas and in Afghanistan. In the post cold war period there were a number unilateral aggressions undertaken by the United States for its own global hegemonic designs like in Afghanistan, Iraq and Libya etc. But the end result of these was the US failure to shape global reality as per its own designs that considerably dented its prestige and influence. It inflicted considerable human loss, social dislocation and physical and economic destruction in the affected countries.
Historically speaking the violence has been used as a medium of politics i.e. as instrument of expansion and exploitation by the dominant and as the mechanism of resistance and defiance by the weak, oppressed and aggrieved. Historically it manifested more as interstate wars. But along with that there has been non state agencies and groups engaged with violent campaigns as a mechanism of achieving various types of political goals. There have been many of the contentious issues born out of the colonialism that have resulted in (and continue to cause) violent conflicts. However, after World War II, more so during last few decades, there are strong reasons for serious rethinking on war and violent conflicts being viable and feasible means of attaining political objectives and resolving issues. It was the countries in the Europe that initially recognised this emerging phenomenon. After having suffered the calamitous effects caused by the two great wars the countries there realized the value of living in peace. Europe has made a number of strides in evolving a new paradigm of relationship based on peaceful coexistence, open borders, reconciling individual nationalism to cooperative living thereby creating a new example of relationship for rest of the world to follow. Today European Union should define the evolving order that the countries in other regions of the world need to emulate.