The Monroe Doctrine, issued in 1823, stated that the Western Hemisphere was now, and forever, off limits to the European powers. At the time, much of Latin America was beginning to gain independence from a much weakened Spanish Empire and the United States wanted to ensure that a separate European power – such as England or France, would not take the place of Spain. The Doctrine also assured Europe that the United States would not intervene in the affairs of European nations elsewhere in the world.

The Spanish-American War lasted a mere three months, and resulted in the deaths of relatively few Americans. As a result it was roundly viewed as a spectacular success in the United States. After the destruction of their fleet, and battle losses in Cuba and the Southern Pacific, the Spanish sued for peace. The Americans agreed on the terms that Cuba should be liberated from Spanish rule (it was placed temporarily under American control, but gained full independence four years later), and that America would annex Puerto Rico, Guam and the Philippines. Defeat in the war and substantial loss of territory spelled the effectual end of Spain as a global power. Therefore, all the answer choices here are correct. Additionally, the war spelled an ascension to world power status for the United States and helped quell social unrest domestically. 

The Jay Treaty, signed in 1794, was a successful attempt by the United States and the British Empire to avert war and resolve some disputes that had existed since the signing of the Treaty of Paris, eleven years prior. The Treaty assured the United States that the British would abandon their forts and military stations still held in American territory. It also granted the United States certain trading rights with British possessions, in exchange for British rights to American cotton. The Jay Treaty successfully averted war, but an attempt at a replacement treaty ten years later failed and, in 1812, the United States and Britain would fight a second war in an attempt to resolve their existing differences. The Jay Treaty was also crucial in solidifying the early identities of the Federalists (pro-big business; pro-British) and the Democratic-Republicans (pro-agriculture; pro-French). 

The Chesapeake-Leopard Incident was a brief naval conflict that occurred between Great Britain and the United States in 1807. The British HMS Leopard attacked and boarded the USS Chesapeake to capture and try deserters. This policy of impressment was common practice in the British Empire, but, to most Americans, the attack represented an insulting incursion upon American sovereignty. The incident escalated tensions between Britain and the United States almost to the point of war, but Congress balked at open warfare with the British Empire and Jefferson issued the Embargo of 1807. War would have to wait a further five years of escalating tensions and naval engagements. 

The Aroostook War was an international incident between the British and the United States. Both sides claimed greater territory in the New Brunswick and Maine region that the other side was willing to concede. The word “war” was used somewhat ironically, as conflict never broke out, but forces from both sides were stationed prepared for conflict. Eventually a diplomatic resolution was worked out in the Webster-Ashburton Treaty in 1842. 

The Treaty of Wang Hya was signed between the United States and China in 1844. The treaty allowed American merchants to trade in Chinese ports and goods. It also placed the United States on an equal relationship with China as only Britain had previously enjoyed. It represents the first of a series of attempts to better relations between the United States and China. 

French Emperor Napoleon Bonaparte, needing to finance his wars across Europe, sold all remaining French possessions in America to the United States in 1803. This land went from New Orleans, up the Mississippi River, and across to the Rocky Mountains. President Thomas Jefferson had already sent Meriwether Lewis and William Clark at the head of an expedition to explore much of this territory for the US government in late 1802. Lewis and Clark actually went further than the new Louisiana Territory, and made the Pacific.

President James Monroe outlined the Monroe Doctrine in his seventh State of the Union in December 1823.  Responding to various colonial revolutions throughout the Americas, Monroe wished to establish solidarity with the young republics in North and South America, as well as protecting American interests from European incursions.