Laird was 94.
In 1969, at the peak of the Vietnam War, Laird joined President Richard Nixon's administration as the secretary of defense.
Before joining the Cabinet, Laird had been an influential Republican congressman representing Wisconsin for 16 years with an expertise in defense and military matters. He was a well-respected World World II veteran and Purple Heart recipient.
Laird had become a vocal critic of President Lyndon B. Johnson and his secretary of defense, Robert McNamara's policy on the Vietnam War.
Laird had several goals as secretary of defense. He wanted to end the draft, disengage from the war and reach a peace settlement.
"Wars are easy to enter into," he said in 2010.
"They're very difficult to get out of."
Laird pushed a policy of "Vietnamization," which meant withdrawing US forces while equipping and training South Vietnam's military.
He also instituted sweeping changes in US foreign and defense policy, most importantly by shifting the US military from a conscripted army to an all-volunteer force.
it was a matter of equity. "It is pretty much an economic issue because conscript labor -- paying young men in the military very low rates -- was unfair."
"Yes, it was a difficult fight ... but I maintained and by the time I left the White House, there was no draft."
US Secretary of Defense Ash Carter praised Laird's contributions in a statement issued Wednesday.
"Secretary Laird led the Defense Department through a time of great change in the world and within our department. Through it all, he demonstrated an unfailing commitment to protecting our country, strengthening our military, and making a better world."
Laird also publicly highlighted the inhumane treatment of American prisoners of war and pushed for their return.
"Those of us who fought and those of us held prisoner in Vietnam will always have a special place in our hearts for Sec Melvin Laird," tweeted Sen. John McCain.
Laird stepped down in 1973, serving four years in the administration as he had vowed to do.
Legacy outside of Vietnam policy
Born in Omaha, Laird came from a family in which both parents
had held political office. It seemed natural that he should enter politics.
He represented the Wisconsin's 7th Congressional District from 1953 to 1969.
Laird and Democrat Congressman John E. Fogarty, from Rhode Island, formed a bipartisan alliance to expand federal funding for medical research projects and institutions -- including the National Institutes of Health, National Library of Medicine and the Centers for Disease Control and Prevention.
"It was a great start to what ultimately became the reward of the NIH to the nation and to the world, with its research resulting in better health care for people all over the world," Laird said in a 2014 interview.
The Laird Center for Medical Research in Wisconsin is named after him as a tribute to his health advocacy.
"His work helped shape medical research as we know it," said Dr. Susan Turney CEO of the Marshfield Clinic Health System where the Laird Center is based.
Laird had fondly looked back on his days working across the aisle with Fogarty.
"The two of us put aside our party affiliations and worked ... to prove how working together could build a national program for health research and education that would be the envy of the world," he said in a 2014 interview.