GOP Rep. Tom Cotton, the newest senator from Arkansas, completed the Republican takeover of that state’s congressional delegation Tuesday.

Cotton is an Army veteran who served one term in the House. Raised in Dardanelle, Ark., a town of less than 5,000 just over an hour northwest of Little Rock, Cotton joined the Army in 2005 after receiving his law degree from Harvard and served in Iraq and Afghanistan.

In 2006, after the New York Times published a story on efforts to track terrorist financing, Cotton e-mailed a letter to the newspaper, critical of their decision to expose U.S. strategy. “You may think you have done a public service, but you have gravely endangered the lives of my soldiers and all other soldiers and innocent Iraqis here,” he wrote.

The Times did not run his letter, but Cotton gave a copy to the conservative Power Line blog, which published it. His letter went viral in conservative circles online, and readers were impressed with his resume as an Ivy League-educated Army lieutenant who practiced law with two firms in Washington. Some liberals questioned whether he was even real, according to Power Line’s John Hinderaker, a Minnesota attorney. “They couldn’t imagine there was someone who graduated from Harvard who’d enlist,” Hinderaker said.

In 2013 after taking office, Politico named him “most likely to succeed,” citing his support from Republicans as varied as former Arkansas governor Mike Huckabee and Sen. John McCain (R-Ariz.). On the campaign trail, Cotton emphasized his red-state credentials, tying Sen. Mark Pryor (D-Ark.) to President Obama and decking out his campaign bus in camouflage with a with a red, white and blue bootprint on the front. Campaign ads frequently featured photos of his time in the Army.

Cotton, who is 6-foot-5, married his wife Anna earlier this year, and they are expecting their first child in April.