Obama used the phrase in his response to Romney's critical comment about the size of the U.S. Navy being smaller now than it was in 1916.
"You mention the Navy, for example, and that we have fewer ships than we did in 1916. Well, governor, we also have fewer horses and bayonets because the nature of our military has changed," Obama said. "We have these things called aircraft carriers, where planes land on them. We have these ships that go underwater, nuclear submarines. And so the question is not a game of Battleship, where we're counting ships."
The phrase "horses and bayonet"s was the top debate-related search term during the debate, according to Google search data.
The hashtag "horsesandbayonets" began trending on Twitter following Obama's response and Facebook users created pages named after the phrase.
Along with "horses and bayonets," Americans were also searching other military terms during the debate, including Drones and Syria.