This seems to me like the kind of claim that can only be supported with a ton of goalpost moving on the terms of "peace," "transfer," and "party" against counter-examples.

EG 1 In 1714 the Throne of England was transferred from the House of Stuart to the House of Hanover. I would call this a peaceful transfer, but a) is this "between parties"? and b) does the Jacobite uprising of 1715 (a branch of the House of Stuart who had in 1688/89 been violently deposed led an armed rebellion) disqualify it as "Peaceful"? Similar questions could be asked of the transition from Tudor to Stuart England.

EG 2 The Restoration of Charles II was hailed as largely peaceful, with the general tone of the Declaration of Breda being of forgiveness and peace. Does the exclusion of the regicides from that forgiveness, with their subsequent prosecution and execution disqualify that from being "peaceful"? Does this qualify as a "transfer between parties"? Again, I think this meets your teacher's definition, but the goal posts could again simply be moved.

E3 Queen Anne's Tory ministry (1711-14) led by Robert Harley both entered and exited power without violence, but his rise and fall wasn't tied to any election, rather simply shifts in Royal favour (and the rise of the house of Hanover). But this is definitely a party affair. Does it count as a transfer? And what about the rise and eventual fall of the Walpole Whig Ministry which followed him?

What your teacher is saying feels misleading. Maybe its the cynic in me but it seems to me that he/she is trying to paint a picture whereby the first US election is the first and world leading democratic process that didn't involve war/revolution/hereditary monarchy and so on but that's simply not true.

In Britain, peaceful elections had occurred at least 100 years before that. Problem, is how you define parties. Power transitioned between the Whigs and the Tories throughout 18th century Britain peacefully at general elections. Problem is, the parties then weren't really properly formed organisations in the modern mould. More a loosely associated group of people with similar ideas and goals. But it is still power transferring peacefully from one party to the other. Universal suffrage wasn't in place at this time of course (but that can be said of the USA as well) and there was corruption aplenty so you can discuss and question the democratic credentials of these elections.

I don't know anything about 17th century English elections but perhaps someone else can fill in the blanks there if relevant. British elections began after the Act of Union in 1707 (Union of England and Scotland) and there were numerous different prime ministers across the rest of that century.

There were of course very many peaceful transitions of power in the Roman Republic (after the Kings, before the empire) as power transferred peacefully every year from one pair of consuls to another after general elections, but again, there is a lack of political parties here.

I guess the point I'm making is that if your teacher's point is about unified political parties then he/she may have a point but I certainly don't have the world knowledge to comment - various experts in different fields would have to come here and answer for their own geographical areas of expertise.

But if your teacher's point is about the USA pioneering peaceful transition of power, they are most definitely wrong by at least a couple of thousand years, perhaps more. There is both recent and ancient history (as per my above examples) to demonstrate this.

Do you happen to live in Virginia? I'm a history teacher in Virginia and that very phrase is part of our standards. Even though most of us know it's misleading, it'll inevitably be on the SOL every year. This is what happens when politicians are in charge of the standards!