The American Revolution
The American Revolution was fought as a way to ensure the liberty of every colonist from British tyranny. However, despite this, female colonists weren't given the same liberty as their male counterparts, ironically suggesting that men and women aren't equal, as the Declaration of Independence and Constitution said.
Ormond
Ormond is initially portrayed as a cultured, sophisticated, and charming individual who is often willing and able to help other people be successful. At first glance, he appears to be a kind-hearted person. However, Ormond is ironically manipulative and threatening; he poses a tremendous risk to Constantia.
Violence
Despite engaging in violent acts to fight the Revolutionary War and free themselves from British rule, American colonists ironically actively discouraged violence as a means to an end.
Yellow Fever
Many characters in the novel, especially Constantia, think that infection from Yellow Fever is the greatest threat they face. Ironically, the greatest threat they face is from other characters in the novel, something readers are aware of, but the characters in the book are not.