The first president to get married while in office was John Tyler. John Tyler was also the first president to have his wife die while in office.
Theodore was the first sitting president to leave the country. He visited Panama while he was president.
The Korean War began while Truman was the president.
John Adams
I guess that would have been the War of 1812, which started 200 years ago this April. James Madison was U. S. President at that time.
William Henry Harrison was the first US president to die in office.
Thomas Riley Marshall from Indiana was serving as vice-president under Wilson in 1920 when Harding ran for president. Harding's running mate was Calvin Coolidge and both were elected.
Theodore took a trip to Panama while he was president.
It was President Washington.
Theodore Roosevelt, the nation's 26th President, was the first president to visit a foreign country while serving in office. Roosevelt was a member of the Republican Party.
His very first was to pardon Nixon for his crimes while president.
While President Nixon was a big supporter of space exploration, it was President Kennedy who actually started federal funding to finance it. It could be said, Kennedy started the space race.