The US and UK started out as opponents and eventually became friends though various means.

To say that when the American Revolution ended that the United States and the British Empire were not friendly is an understatement. They literally just ended a war with one another so it makes total sense that they would not get off to a good start diplomatically. This is somewhat true as the US and UK still did trade with one another and retained many economic ties. So while they were not friendly, they at the same time were not too disliking of one another. For example, the US borrowed money to pay for the Louisiana purchase from British banks.

This would change with the war of 1812. The US no UK went to war with one another for various reasons which includes the imprisonment of sailors. The war started out very poorly for the Americans who were beaten and saw the White House burned to the ground. But eventually the Americans won a battle in New Orleans, granted the war was over at that point. Nothing really changed in the peace deal. Both nations went back to trading and maintaining economic ties but disliking one another. There are also political reasons for this besides the US breaking away as a colony. The Americans were a “liberal” nation where as most European nations were “conservative” the difference is that the US practiced the ideas of the enlightenment differently than the UK. Not to mention the UK just fought a war with a “liberal” France.

The US and UK had their own interest in the 19th centuries which would see them become friendlier. But there were hiccups. The US did not care for European politics and instead focused on the continental United States. The Monroe doctrine stated that no European powers would involve themselves in the Western Hemisphere. The British of course had Canada and a couple other colonies but their main focus was India and European politics so they were willing to agree to the Monroe doctrine.

Both nations had similar motives and goals which actually saw them work side by side. The main goal was to end the slave trade and British and American ships ( mostly British but there were American ships ) patrolled the Atlantic and eventually slowed and halted the Atlantic slave trade. This was not an “alliance” but more of both nations just having a common goal.

The real issue would come during the American civil war. The UK relied on cotton imports from the US and did not like the civil war and union blockade of the south. But the real issue was the Trent Affair in which Union ships seized confederate diplomats heading to the UK. The British were outraged saying it was not up to the US to allow the British to talk to different nations. The Union eventually released the diplomats calming the whole affair down. This hurt the affairs of both nations and the US and UK were pretty annoyed with one another. However, the British couldn’t intervene in the American civil war for various reasons including public opinion. Both nations eventually looked past this issue.

The late 19th century would see both nations relationship improve dramatically. First off, the UK had a new opponent and that was the German empire. The Germans and British eventually became locked in a naval arms race which was very crippling for the British. America and the UK eventually came up with a decent soultion to help the British navy. US ships would protect Caribbean islands under British rule. This allowed British ships to return to Europe to compete with the Germans. This also allowed American ships to be better freed up for the Pacific as it looked like a war could start between Japan and America.

The Anglo-German arms race improved Anglo-American relations. But other events did too. This period saw American and Britain side more and more with one another on various issues. The treatment of the Congolese by the Belgians saw a joint American and British outrage. Not to mention the cultural and religious ties that both nations shared at this time. A lot of minor issues occurred too. In Persia, British diplomats sometimes protected American missionaries for example.

Of course there were minor issues like territorial disputes. The US and UK/Russia also faced off in Persia with many Americans being upset at British treatment of the Persians. Not to mention the cultural fact that the Americans were anti imperialism ( well kind of ) and the British were an empire.

I hope my response helps. It is a very basic guide to Anglo-American relations before ww1/ ww2. I recommend “the war that ended peace” to better understand the topic. It’s by Margret MacMillian and is actually a free audio book I believe.