In 1978, American political scientist Walter Vella stated, “Like any system of loyalty, nationalism has its virtues and its faults. Its good lies in its power to unite; its bad lies in its power to divide.” This assessment of nationalism has never gone out of fashion. The current state of Thai–Cambodian relations has been ostensibly moulded by the powerful, yet dangerous, sentiment of nationalism which has its deep roots in the bitter historical intercourse between the two kingdoms. In their modern-day context, the ransacking of the Royal Thai Embassy in Phnom Penh in January 2003 and the recent eruption of armed conflicts between Thailand and Cambodia over the Hindu Temple of Preah Vihear, known in Thai as Phra Viharn, exemplifies the work of nationalism and the impact caused by historical overhangs or legacies on this fragile relationship. Nationalism has over the years been exploited by the two countries’ political leaders to fulfil a myriad of their own political interests. Nationalism has been capable in many instances of driving them into confrontations, and even war. While the rationale behind nationalism might be discursive, nationalism in itself is a systematic construct. Countries fabricate history to celebrate their past, using nationalism as a political tool in their manipulation of public opinion. As history is remodelled for political agendas, old wounds are reopened. Past bilateral conflicts are refreshed. It is evident that contemporary Thai–Cambodian relations have become a casualty of the remade past.

This chapter examines how history has been distorted and nationalism employed to serve the power interests of the Thai and Cambodian leaders. It discusses the implications of the historical overhang or legacy on today's interactions between Thailand and Cambodia, and elucidates why and how such a phenomenon has endured despite the fact that the international environment has consistently changed. The chapter argues that historical overhangs or legacies have been firmly sustained and have frequently emerged as a primary determining factor in Thai–Cambodian relations, particularly whenever their political leaders encountered legitimacy crises at home. To divert the people's attention from domestic issues, leaders fanned the flame of nationalism while making enemies across the border.

The military coup of 2006 that deposed the elected government of Prime Minister Thaksin Shinawatra led to an increasing militarization of Thai politics. This latest political intervention unveiled the calculated strategy of the military. Not only did the coup serve to eliminate the traditional elite's enemy, in this case Thaksin, but it also opened the door for the military to reclaim its control over politics, and consequently, foreign policy. The role of the military in foreign affairs was immense during the Cold War period. The threat of communism in this part of the world allowed the military to entrench its position in the name of defending national security, with the support from the United States, both in ideological and financial terms. But this role was challenged when Thaksin became prime minister in 2001. Throughout the Thaksin administration (2001–06), Thaksin intruded in the military's affairs, diminishing its influence in domestic politics and foreign policy making. Daringly, Thaksin attempted to fragment the army so as to prevent a possible coup. But Thaksin eventually failed. For the military, the only way to regain its political power was to stage a coup against Thaksin. The political turmoil that followed in the post-coup years, in turn, legitimized the military's political position. The military firmly took charge of the uncertain political situation, particularly in dealing with security issues, such as endless street protests and occasional violent confrontations with certain political factions.

In 2008, the pro-Thaksin regime of Samak Sundaravej returned to power through the first election after the coup. The election victory of the People's Power Party (PPP), a reincarnation of Thaksin's disbanded Thai Rak Thai Party (TRT), was a slap in the face for the military elite who were certain that the coup was an effective measure in deracinating Thaksin's political legacy. To destabilize the Samak government, the yellow-shirt People's Alliance for Democracy (PAD) took to the streets of Bangkok, politicizing the issue of Preah Vihear, known in Thai as Khao Phra Wihan.

In the evening of 19 September 2006, the military staged the eighteenth coup since the abolition of absolute monarchy in 1932, overthrowing the elected government of Thaksin Shinawatra. Although Thailand adopted a democratic model of governance to replace the ancien régime, the military has imposingly dominated the Thai political space throughout the past eighty years. It has worked intimately with the monarchy in cultivating a particular kind of politics whereby civilian governments are kept vulnerable, or face the possibility of being toppled should they pose a menace to the power position of the traditional elite. Under these conditions, coups were therefore not uncommon, especially as a tool to undermine a strong civilian government. The military's political intervention has become part of Thai political culture. Often, there have been attempts on the part of the military to legitimize the coups as a moral instrument in the riddance of immoral civilian regimes. From 2001 to 2006, Prime Minister Thaksin Shinawatra enjoyed electoral popularity, and thus managed to firmly consolidate his grip on power. He won two landslide elections, in 2001 and 2005, becoming the only prime minister who had ever served a full four-year term in Thai history. But his intensifying political strength gravely worried the traditional elite. They perceived him as a threat to their long-held political influence. With political interests in jeopardy, and in exercising the old trick, the traditional elite removed the Thaksin regime with the bluntest of tools; a military coup. They accused Thaksin of displaying disrespect for the King and committing corruption, among other things. These accusations served to justify the unlawful coup as a necessity to punish the fraudulent government of Thaksin. A large number of middle-class Bangkok residents came out to lend their support for the coup; they were seen offering food and flowers to Thai soldiers who seized power on that ill-fated night.