The solution to today's Quiz has been verified carefully, so there is no need to worry that we'll have an unfortunate discrepancy as occurred with last week's festivities.

U.S. President Dwight D. Eisenhower did this particular Presidential thing twice during his time in office, both times in the year 1959. Only two previous twentieth-century U.S. Presidents had ever done it before. Eisenhower never did it again, and in fact neither has any U.S. President since (though it could still happen).

What was the thing President Eisenhower did?

The answer will come to you without Googling, if you'll just believe in yourself, dammit. One well-informed guess per comment please, though you may comment as often as you like. First correct answer posted to comments wins a packet of dried-up but genuine "Brooklyn" brand chewing gum.