None of America’s first twenty-six Presidents—spanning a hundred and twenty years—held a summit. None of them even got to Europe while in office. Woodrow Wilson was the first to travel across the Atlantic, when he went to Paris for peace talks to end the First World War. That summit still holds records. Wilson spent six months in France, with one short break back home. He met his three major counterparts—from Britain, France, and Italy—a hundred and forty-five times to craft the 1919 Treaty of Versailles. It was, at the time, the widest-ranging peace pact ever negotiated. It reconfigured the international order. It redrew borders. And it created the League of Nations—the first global institution and the seed of others to follow—to avoid future wars.

For Wilson, however, the summit was a domestic and international flop, even though he won the 1919 Nobel Peace Prize. Congress refused to ratify the Treaty of Versailles, over objections to the League of Nations. The collapse paved the way for American isolationism during the next three Presidencies. The summit had global fallout, too. German bitterness over the treaty’s terms generated backlash, which the Nazis exploited politically in their rise to power, and a far deadlier world war, two decades later.

Summitry, especially on issues of war and peace, can be the most complex diplomatic undertaking—as President Trump is learning with North Korea. Meetings of heads of state often take place after years of false starts. Trump has repeatedly blamed Presidents Bill Clinton, George W. Bush, and Barack Obama for not disarming North Korea earlier, yet he is building on principles of denuclearization developed by his three predecessors.