Rep. John Murtha, the Pennsylvania Democrat best known for speaking out for veterans and against the Iraq war, died Monday. He was 77.

Murtha had been suffering complications from gallbladder surgery. He passed away at the Virginia Hospital Center in Arlington, Va., with family members by his side.

Murtha, a former Marine, was the first Vietnam War combat veteran elected to Congress. He soon became an influential voice of veterans on Capital Hill.

"He understood the misery of war," fellow Democratic Rep. David Obey said. "Every person who serves in the military has lost an advocate and a good friend today."

Though Murtha initially voted in 2002 to authorize President George W. Bush to use military force in Iraq, he called for an immediate withdrawal of U.S. troops in 2005 after growing frustrated with the war. One year later, he accused Marines of murdering Iraqi civilians "in cold blood" at Haditha, Iraq.

"The war in Iraq is not going as advertised," he once said. "It is a flawed policy wrapped in illusion."

Though Murtha was known for his seriousness, especially when it came to military issues, Pennsylvania Gov. Ed Rendell remembered him as a "funny guy."

"He always enjoyed a good laugh and he was somebody who was a great and loyal friend," Rendell said.

Murtha won re-election in 2008. His congressional seat will now be up for grabs in the upcoming November election