Douglas C. Roach, the longtime staff director for the House Armed Services Subcommittee on Tactical Air and Land Forces, died Jan. 11. He was 70.

Roach was a cornerstone of every defense authorization law since 1991 — whether as a professional staff member on the Tactical Air and Land Forces panel, or its staff director since 2001 — under both Democrats and Republicans.

He led a distinguished career of public service beginning in the Air Force, including 516 combat missions between 1969 and 1972.

Roach died at Sibley Memorial Hospital in Washington from complications related to cancer, according to House Armed Services panel spokesman Claude Chafin.

Determined, forthright and, at times, obstinate, Roach’s death came after a series of chemotherapy sessions when he developed pneumonia.

“This weekend, America lost a selfless servant and true hero,” said House Armed Services Chairman Howard “Buck” McKeon, R-Calif. “Doug Roach was more than a member of my staff; he was an institution.”

Roach served leaders of both parties, often acknowledging the political challenges that members of each party faced as they worked through important national security legislation.

“Doug Roach was a trusted counselor to members on both sides of the aisle for many years,” Rep. Michael R. Turner, the Ohio Republican who chairs the Tactical Air and Land Forces panel, said in a written statement. “He always gave us his best advice, regardless of party interest or agenda.”

“Doug Roach was a war hero, a dedicated public servant, and a selfless man. He was also my friend,” Rep. Adam Smith, D-Wash., the ranking member on Armed Services, said in a written statement. “He cannot be replaced, and he will be deeply missed.”

Roach was a strong ally and tough opponent in his interactions with the U.S. military, sensitive to the military’s needs and, often, skeptical of its demands.

Doug Bush, a professional staffer on the House panel, noted that Roach’s vast experience informed staff in direct and indirect ways.

In an email, Bush recalled a moment that reflected the kind of leader Roach was. Bush, who oversees land combat systems developed by the Army, joined the committee five years ago, when the Army was attempting to develop its ambitious — and doomed — Future Combat System, a complicated mix of networked combat vehicles and other equipment. The ill-defined and overly complex program was hobbled by an excessive overlapping of development, production and testing.

“My first week on the HASC staff, Doug Roach and I were talking about Army programs, and FCS in particular,” Bush wrote. “I remember him saying, ‘I’ll let you form your own opinion on FCS, but from the start I’ve thought the whole thing was just kind of stupid.’”

The program was ultimately canceled.

Most of the time, Roach was a strong proponent of allowing the military to set its own course. But he became more personally involved in some programs.

In particular, he was a strong proponent of the controversial alternative engine program for the multiservice F-35 Joint Strike Fighter program.

Roach was a strong believer that building a second type of engine — pitting Pratt & Whitney, the core engine developer for the F-35, against General Electric — would play an important role in driving down the cost of the $100 billion engine program while also helping to improve the performance of both engines.

But the Pentagon decided over time to cancel the alternative engine as a cost-cutting measure, a move resisted by many in Congress.

One senior House defense panel aide recalled a meeting before a critical vote on the engine in 2010 when Ashton B. Carter, then the Pentagon’s acquisition chief, met with several dozen staffers and members in the Capitol.

“After Carter made brief remarks, Doug Roach then took over the event by jumping up and interrupting Dr. Carter numerous times with very pointed questions like ‘Mr. Secretary, that last statement just isn’t accurate’ and ‘Mr. Secretary, there is just no factual basis for that statement,’” the aide said. “I remember admiring his bravery in going after a senior DOD official, and so publicly, to fight for something he thought was right. I also remember admiring his ability to keep his cool and stay professional as he did it.”

For several years, Roach worked with lawmakers to resist the Pentagon’s effort to terminate the GE engine. He often sent lengthy emails, dubbed “Roach clips” by colleagues, to staffers and reporters that critiqued news stories on the engine competition.

“Doug sent clips to staff every day, early,” one senior congressional aide wrote in an email. “Most of the time before 6 a.m.”

In the end, however, Gates succeeded in terminating the second engine. Roach was disappointed in this decision. He argued that it was one way the F-35 program could have gained some control over its maintenance and sustainment costs over its planned 50-year life, which could cost an astounding $1.1 trillion.

Roach could blister the air with foul language in the House Armed Services military hardware offices, known as “the pit,” at some real or perceived injustice, inaccuracy or inanity, but he also was known for his light touches.

“He was the same sweetheart who secretly left Godiva chocolate Santas and Easter bunnies (and, this year, Thanksgiving turkeys, too) on the desks of all the women who worked for HASC,” one senior aide noted. “They weren’t supposed to say ‘thank you’ because they weren’t supposed to know who left them, but they always made the women smile.”

A highly decorated officer who retired with the rank of colonel in the Air Force, Roach was a skilled combat pilot and later served with the Air Force flight performance team, the Thunderbirds.

Roach was born in Romulus, Mich., on Nov. 18, 1942. He earned a bachelor of arts degree in government at the University of Michigan and a master’s degree in national security studies from Georgetown University. He is survived by his brother, Jarmin.

Megan Scully contributed to this report.