His Britannic Majesty and the United States of America desirous of terminating the war which has unhappily subsisted between the two Countries, and of restoring upon principles of perfect reciprocity, Peace, Friendship, and good Understanding between them, have for that purpose appointed their respective Plenipotentiaries, that is to say, His Britannic Majesty on His part has appointed the Right Honourable James Lord Gambier, late Admiral of the White now Admiral of the Red Squadron of His Majesty's Fleet; Henry Goulburn Esquire, a Member of the Imperial Parliament and Under Secretary of State; and William Adams Esquire, Doctor of Civil Laws: (2) And the President of the United States, by and with the advice and consent of the Senate thereof, has appointed John Quincy Adams, James A. Bayard, Henry Clay, Jonathan Russell, and Albert Gallatin, Citizens of the United States; who, after a reciprocal communication of their respective Full Powers, have agreed upon the following Articles. (Intro.1-2)

There's a lot of buddy-buddy talk going on in the first line of the Treaty of Ghent. Listen to all those happy words: friendship, perfect reciprocity, good understanding. From reading the opening lines you wouldn't suspect that, during negotiations, they were still killing each other in New Orleans and Baltimore.

The opening is essentially a statement of purpose. Both countries want to end the war. Obviously that's the goal of most treaties. The tone of the opening here is very similar to the 1783 Treaty of Paris.  If you're ever writing a peace treaty, you could pretty much copy and paste this intro. Although, you'd want to reword some things to avoid plagiarism—and sounding like you live in the 19th century.

The second part of the opening paragraph introduces our cast of characters: the ambassadors who hammered out this peace agreement. Our authors are referred to as "Plenipotentiaries," a word that basically means a diplomat who's given independent authority to make decisions on behalf of the government. They had to have that authority, because if they had to keep checking back with their superiors in America, say, the negotiations would have taken ten years.

All the plenipotentiaries get their props here: their titles are listed, they're fully authorized to conduct these negotiations by the King and the Prez, and they've managed to agree on everything that follows.

It's a promising intro, designed to win over any doubters and let everyone know that the British and Americans are pledging to be BFFs.