In a Fourth of July speech dedicated largely to American military might, Donald Trump claimed US Army troops “took over the airports” during a conflict which broke out almost a century before the first planes took flight. Allaying fears he would turn the "Salute to America" address at the Lincoln Memorial into a campaign-style rally, Mr Trump avoided political point-scoring and kept largely to a script, part of which detailed American military achievements throughout history.“Our army manned the amparts (sic), it ranned (sic) the ramparts, it took over the airports, it did everything it had to do,” Mr Trump said, apparently struggling to read from the autocue. Though it was unclear if he was referring to a moment during the Revolutionary War or the later War of 1812, which was also fought between British and American troops, Mr Trump was out by at least 89 years – the Wright brothers would not pilot the first powered flight until 1903.The comment sparked mockery from some of the president’s critics. “This is a president too stupid to know what he’s saying, a White House too incompetent to do basic fact checking, or someone with a serious reading problem,” tweeted Chris Lu, former deputy secretary of labour in the Obama administration. Andrew Stroehlein, a director at Human Rights Watch, sarcastically hailed Britain’s “legendary” air superiority in 18th century conflicts. Mr Trump’s slip of the tongue came just days after he appeared confounded by questions about school “busing” and “Western-style democratic liberalism” during a press conference at the G20 in Japan. Asked about Vladimir Putin’s claim liberalism was in decline, Mr Trump appeared to believe it was a reference to “liberals” in California, and launched into a rant against the leadership in Los Angeles and San Francisco. He also appeared to believe a question about busing – a method intended to help achieve racial integration in schools – was literally just about buses. “I mean, you know, there aren’t that many ways you’re going to get people to schools,” Mr Trump said.