Obama’s broadside reply to Romney’s shot at the size of the Navy took off instantly on social networks and dominated online discussion of the candidates’ final debate.

Additional Photos

President Barack Obama speaks during the third presidential debate with Republican presidential nominee Mitt Romney at Lynn University, Monday, Oct. 22, 2012, in Boca Raton, Fla. (AP Photo/Eric Gay) AP

A look at some key online trends from the night:

Horses and bayonets

The exchange started with Romney challenging his Democratic opponent by saying the Navy is too small and has fewer ships than it did in 1916.

Obama’s response: “Well, governor, we also have fewer horses and bayonets. … 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 online reaction was swift.

On Twitter, the hashtag “horsesandbayonets” immediately began trending in the United States and became the top trend in the country and third worldwide, even an hour after the debate ended. On Facebook, users created more than 50 pages named “Horses and Bayonets.” The Democratic Congressional Campaign Committee also pounced, posting a meme declaring “Obama just sank Romney’s battleship” that generated more than 84,000 likes and was shared more than 16,000 times in an hour.

Regions

Iran, Libya, Israel, Syria, Detroit and even Mali all made appearances among Twitter’s trending topics in the United States and worldwide as Obama and Romney sparred on U.S. foreign policy. Bill Maher weighed in with a jab at voters after Romney mentioned al-Qaida’s presence in Mali. Said the comedian on Twitter: “Mitt, you do know that most of America thinks Mali is one of Obama’s daughters, right?”

Bob Schieffer

The veteran CBS newsman was largely spared the same criticism unleashed by the Internet on previous moderators Jim Lehrer and Candy Crowley. He took some ribbing after a gaffe in which he referred to “Obama’s bin Laden,” but received even more praise for saying everyone loves teachers and closing the debate by saying his mom’s advice is “go vote.”

Hope of the Earth

Romney’s reference to America being the hope of the Earth in his closing statement earned him praise from supporters and sarcasm from detractors. It fit with a phrase that went viral on Twitter earlier in the debate, in which he said his goal is a “peaceful planet.”

The main event

On a night with “Monday Night Football” and the St. Louis Cardinals and San Francisco Giants contending for baseball’s National League championship, the debate won heads up on social networks as the events were played simultaneously. Two-thirds of the way through Obama-Romney 3, eight of nine top trending topics on Twitter in the United States were related to the debate. Even in the moments after San Francisco clinched a berth to its second World Series in three years, the “horsesandbayonets” hashtag was more popular.