The Monroe Doctrine states that the United States will prevent any further European imperialism in the American hemisphere through diplomacy and military force if necessary. The Roosevelt Corollary, added to the Monroe Doctrine by Theodore Roosevelt in 1904, redefined exactly what was acceptable practice for the United States in the issue of imperialism. Roosevelt declared that the United States had the right to intervene in any kind of conflict, even in support of a European power, if the conflict is fomenting unrest and chaos in the Western hemisphere.

The Seven Years’ War was a global conflict fought between the two imperial powers of France and Britain. In the North American theatre the conflict has come to be called the French and Indian War. Many Native Americans fought on the side of Britain and the colonists against the French. The war resulted in victory for the British (including Britain taking control of the subcontinent of India), but led indirectly to the American Revolution.

The Berlin Conference took place in 1884 and 1885 and coincided with Germany’s emergence as a prominent European and imperial power. At the Berlin Conference, the European imperial powers sought to divide the entire continent of Africa among themselves.

The Treaty of Nanking ended the First Opium War between Britain and China. The treaty was an unequal one, as it resulted in numerous concessions being offered by the Chinese and none being offered by the British. The treaty opened China up to European trade and gave the territory of Hong Kong over to British control.

In the Sepoy Mutiny of 1857, Indian troops serving the British revolted against British rule, but were defeated, and the British government took direct control of British India from the East India Company shortly after. The Seven Years' War and the battle of Plassey occurred a century earlier, and simply marked the start of British dominance in India. The massacre of Amritsar and World War II both occurred in the 20th century, long after direct British rule in India started.

The Dutch East India Company was arguably the world's first large scale corporation with a monopoly over the Asian markets. This meant that the Company had exclusive control of the extremely lucrative spice trade coming out of the East Indies. The Dutch East India Company operated with full authority over a huge area covering South Africa through India to modern day Indonesia. This lasted until its dissolution in 1800.

Prior to the introduction of opium in China, the Chinese had a very favorable balance of trade with the British and the other European nations. For clarification, a favorable balance of trade is when you export more than you import. To the mercantilist European powers, this seemed to suggest that China was benefitting more from exchange with the Europeans than the Europeans were. To combat this situation, the British furiously introduced opium into China, fostering individual and community dependence on the drug and then increasing the price of it. The result was an economically stagnant nation whose favorable balance of trade swiftly disappeared.

Matthew Perry was a commodore in the U.S. Navy for several decades. He is most well-remembered for his forcible role in opening up Western trade with Japan in the 1850s. At the time, Japan was operating under a “closed country” policy that heavily restricted official trade with all the Western powers. Perry, acting on the orders of President Millard Fillmore, threatened the Japanese with destruction at the hands of superior American technology and backed up his threats with several “demonstrations.” The Japanese, fearing complete annihilation, acquiesced to all of Perry’s demands and opened up trade with the United States. 

The Treaty of Kangawa granted the United States exclusive trading rights with Japan. Prior to the signing of the Treaty, Japan had operated as a “closed country”; this meant that the Japanese people were forbidden from trading with any of the Western powers. The United States’ Commodore Matthew Perry gained trading rights with Japan through a spectacular and threatening display of technological might that sufficiently intimidated the Japanese officials such that they were left with little choice but to acquiesce to American demands.

The Atlantic slave trade went along routes known as the "triangle trade." Empty ships left northern Europe to go to West Africa, near the present day countries of Ghana, the Ivory Coast, and Liberia, where they would pick up slaves, which then went to the Caribbean, where the slaves were sold and items such as sugar were picked up for European markets. This triangle trade resulted in most American slaves coming from West African tribes and principalities.