Born in Philadelphia, McMaster graduated from the United States Military Academy in 1984, and later earned Ph.D. in American history from the University of North Carolina at Chapel Hill. His Ph.D. thesis was critical of American strategy and military leadership during the Vietnam War and served as the basis for his book, Dereliction of Duty, which was widely read in the United States military. During the Gulf War, McMaster served as a captain in the 2nd Cavalry Regiment, taking part in the Battle of 73 Easting.
After the Gulf War, McMaster served as a military history professor at the United States Military Academy and held a series of staff positions in the United States Central Command. In 2004, he took command of the 3rd Cavalry Regiment and fought the Iraqi insurgency in Tal Afar. He became a top counter-insurgency adviser to General David Petraeus before serving as the Director of the Army Capabilities Integration Center. He also served as the Deputy to the Commander for Planning of the International Security Assistance Force in Afghanistan and, in 2012, he became Deputy Commanding General of the Army Training and Doctrine Command.
In February 2017, McMaster succeeded Michael Flynn as President Trump's National Security Adviser. He remains on active duty as a Lieutenant General of the United States Army.
McMaster was born in Philadelphia on July 24, 1962. He went to high school at Valley Forge Military Academy, graduating in 1980. He earned a commission as a second lieutenant upon graduating from the United States Military Academy at West Point in 1984. McMaster earned a Master of Arts and Ph.D. in American history from the University of North Carolina at Chapel Hill (UNC). His thesis was critical of American strategy in the Vietnam War, which was further detailed in his 1997 book Dereliction of Duty.
Dereliction of Duty: Lyndon Johnson, Robert McNamara, The Joint Chiefs of Staff, and the Lies that Led to Vietnam is a book written by McMaster that explores the military's role in the policies of the Vietnam War. The book was based on his Ph.D. dissertation at UNC. It harshly criticized high-ranking officers of that era, arguing that they inadequately challenged Defense Secretary Robert McNamara and President Lyndon Johnson on their Vietnam strategy. The book examines McNamara and Johnson's staff alongside the Joint Chiefs of Staff and other high-ranking military officers, and their failure to provide a successful plan of action either to pacify a Viet Cong insurgency or to decisively defeat the North Vietnamese army. McMaster also details why military actions intended to indicate "resolve" or to "communicate" ultimately failed when trying to accomplish sparsely detailed, confusing, and conflicting military objectives. The book was widely read in Pentagon circles and included in military reading lists.
His first assignment after commissioning was to the 2nd Armored Division at Fort Hood, where he served in a variety of platoon and company level leadership assignments with 1st Battalion 66th Armor Regiment. In 1989, McMaster was assigned to the 2nd Armored Cavalry Regiment at Warner Barracks in Bamberg, Germany, where he served until 1992, including deployment to Operation Desert Storm.
During the Gulf War in 1991 he was a captain commanding Eagle Troop of the 2nd Armored Cavalry Regiment at the Battle of 73 Easting. During that battle, though significantly outnumbered and encountering the enemy by surprise as McMaster's lead tank crested a dip in the terrain, the nine tanks of his company destroyed twenty-eight Iraqi Republican Guard tanks without loss in twenty-three minutes.
McMaster was awarded the Silver Star. The battle features in several books about Desert Storm and is widely referred to in US Army training exercises. It also receives coverage in Tom Clancy's 1994 popular non-fiction book Armored Cav. McMaster served as a military history professor at West Point from 1994 to 1996, teaching among other things the battles in which he fought. He graduated from the United States Army Command and General Staff College in 1999.
From 1999 to 2002, McMaster commanded 1st Squadron, 4th Cavalry Regiment, and then took a series of staff positions at U.S. Central Command (USCENTCOM), including planning and operations roles in Iraq.
In his next job, as lieutenant colonel and later colonel, McMaster worked on the staff of USCENTCOM as executive officer to Deputy Commander Lieutenant General John Abizaid. When Abizaid received four-star rank and became Central Command's head, McMaster served as Director, Commander's Advisory Group (CAG), described as the command's brain trust.
In 2003 McMaster completed an Army War College research fellowship at Stanford University's Hoover Institution.
In 2004, he was assigned to command the 3rd Armored Cavalry Regiment (3rd ACR). Shortly after McMaster took command the regiment deployed for its second tour in Iraq and was assigned the mission of securing the city of Tal Afar. That mission culminated in September with Operation Restoring Rights and the defeat of the city's insurgent strongholds. President Bush praised this success, and the PBS show Frontline broadcast a documentary in February 2006 featuring interviews with McMaster. CBS' 60 Minutes produced a similar segment in July, and the operation was the subject of an article in the April 10, 2006, issue of The New Yorker.
Author Tim Harford has written that the pioneering tactics employed by 3rd ACR led to the first success in overcoming the Iraqi insurgency. Prior to 2005, tactics included staying out of dangerous urban areas except on patrols, with US forces returning to their bases each night. These patrols had little success in turning back the insurgency because local Iraqis who feared retaliation would very rarely assist in identifying them to US forces. McMaster deployed his soldiers into Tal Afar on a permanent basis, and once the local population grew confident that they weren't going to withdraw nightly, the citizens began providing information on the insurgents, enabling US forces to target and defeat them.
McMaster passed command of the 3rd ACR on June 29, 2006, and joined the International Institute for Strategic Studies in London, as a Senior Research Associate with a mandate described as "conduct[ing] research to identify opportunities for improved multi-national cooperation and political-military integration in the areas of counterinsurgency, counter-terrorism, and state building", and to devise "better tactics to battle terrorism."
From August 2007 to August 2008 McMaster was part of an "elite team of officers advising US commander" General David Petraeus on counterinsurgency operations while Petraeus directed revision of the Army's Counterinsurgency Field Manual during his command of the Combined Arms Center. Petraeus and most of his team were stationed in Fort Leavenworth at the time but McMaster collaborated remotely, according to senior team member John Nagl.
McMaster was passed over for promotion to Brigadier General in 2006 and 2007, despite his reputation as one of "the most celebrated soldiers of the Iraq War." Though the Army's rationale for whether a given officer is selected or not selected is not made public, McMaster's initial non-selection attracted media attention. However, in late 2007, Secretary of the Army Pete Geren requested General David Petraeus to return from Iraq to take charge of the promotion board as a way to ensure that the best performers in combat received every consideration for advancement, resulting in McMaster's selection along with other Colonels who had been identified as innovative thinkers. The demographics for this board's candidates showed that the predominant Year Group of colonels selected for promotion was 1982, and McMaster was the second officer of his 1984 West Point class promoted to the general officer ranks.
In August 2008, McMaster assumed duties as Director, Concept Development and Experimentation (later renamed Concept Development and Learning), in the Army Capabilities Integration Center (ARCIC) at Fort Monroe, Virginia, part of U.S. Army Training and Doctrine Command. In this position McMaster was involved in preparing doctrine to guide the Army over the next ten to twenty years. He was promoted on June 29, 2009. In July 2010 he was selected to be the J-5, Deputy to the Commander for Planning, at ISAF (International Security Assistance Forces) Headquarters in Kabul, Afghanistan.
McMaster was nominated for Major General on January 23, 2012, and selected to be the commander of the Army's Maneuver Center of Excellence at Ft. Benning. In February 2014, Defense Secretary Chuck Hagel nominated McMaster for Lieutenant General and in July 2014, McMaster pinned on his third star when he began his duties as Deputy Commanding General of the Training and Doctrine Command and Director of TRADOC's Army Capabilities Integration Center.
Army Chief of Staff General Martin Dempsey remarked in 2011 that McMaster was "probably our best Brigadier General." McMaster made Time's list of the 100 most influential people in the world in April 2014. He was hailed as "the architect of the future U.S. Army" in the accompanying piece written by retired Lt. Gen. Dave Barno, who commanded U.S. and allied forces in Afghanistan from 2003 to 2005. "Major General Herbert Raymond McMaster might be the 21st century Army's pre-eminent warrior-thinker," Barno wrote, commenting on McMaster's "impressive command and unconventional exploits in the second Iraq war." Barno also stated, "Recently tapped for his third star, H.R. is also the rarest of soldiers—one who has repeatedly bucked the system and survived to join its senior ranks." In 2014, retired Army Gen. Jack Keane, a former Army vice chief, commented "It is heartening to see the Army reward such an extraordinary general officer who is a thought leader and innovator while also demonstrating sheer brilliance as a wartime brigade commander."
On February 20, 2017, U.S. President Donald Trump named McMaster to serve as his National Security Advisor following the resignation of Michael T. Flynn on February 13. McMaster indicated that he "intends to remain on active duty while he serves as national security adviser."
Because McMaster intended to remain on active duty, his official assumption of the National Security Advisor's duties and responsibilities required a United States Senate vote; lieutenant generals and generals require Senate confirmation of their rank and assignments. On March 6, 2017, the Senate Armed Services Committee voted 23–2 to recommend to the full Senate that McMaster be confirmed for reappointment at his lieutenant general rank during his service as the National Security Advisor. The committee recommendation was referred to the Senate on March 7, and the full Senate confirmed McMaster by a vote of 86–10 on March 15, 2017.
In early August, McMaster was targeted by what some deemed a "smear campaign" after he fired several National Security Council staff members. White House officials and journalists suspected Steve Bannon of leading these attacks. right-wing activists Mike Cernovich and Alex Jones, along with Breitbart, and Russia-linked Twitter accounts, were among the foremost promoters of the anti-McMaster campaign; Cernovich's website for the campaign also included a cartoon depicting McMaster which the ADL labeled antisemitic. This campaign prompted dismissive responses by administration officials, and a statement from Donald Trump affirming his confidence in McMaster.