The two men capped off the first day with a lavish meal atop the Eiffel Tower - followed by a massive Bastille Day celebration on Friday complete with a military parade and centennial commemorations of the entry of U.S. troops into World War I.
During this press conference today, Trump was asked whether he agrees with Christopher Wray, his nominee for Federal Bureau of Investigation director, that someone who is contacted by a person who says they have damaging information on a political opponent coming from a foreign government should contact the Federal Bureau of Investigation. "It's called opposition research or even research into your opponent", he added.
"Today we face new threats from rogue regimes like North Korea, Iran and Syria and the governments that finance and support them".
More than 50,000 Americans died in what then-president Woodrow Wilson described as the "war to end all wars", a conflict that forged the trans-Atlantic alliance in steel.
With full fanfare, complete with honor guards and a band, the American president visited Napoleon's tomb at Les Invalides, a 16th century complex housing medical facilities for veterans, and France's national military museum.
The comments from Trump seemingly remarking on the figure of Brigitte Macron-who is, of course, married to French President Emmanuel Macron-aren't exactly out of character for the USA president.
"There's also a strong political dimension". France, Trump said, was America's first ally. "He (Trump) sometimes takes decisions that we disagree with, on climate change for example", Castaner added.
There are already tensions over climate change and trade, while Trump was openly critical of the European Union a year ago and snubbed a handshake with German Chancellor Angela Merkel during their first meeting in March.
President Trump has managed to step in it again - probably while thinking he was being polite - with a compliment that critics say is singling out the age difference between the 39-year-old French President Emmanuel Macron and his 64-year-old wife Brigitte. "I understand it is important to save jobs". Otherwise, you're going to make me look very bad. Her stepson, Donald Trump, Jr., has monopolized headlines after news of his meeting with a Russian lawyer stirred up more West Wing drama.
One area which has been working normally is the fight against jihadists where France is a partner in the US-led global force operating in Syria and Iraq.
Macron also told Ouest-France that Paris and Washington had "an essential point of convergence: fighting terrorism and protecting our vital interests". "We will see", he said. Earlier in the day, Trump and Brigitte Macron shared what much of social media labelled an "awkward handshake".