President Donald Trump boasted that his administration was staffed with notable members of the US armed forces.

Many of those senior military officials have since left his administration.

Some of these officials have been outspoken in their opposition to Trump's policies, like former chief of staff John Kelly, who called one recent Trump decision "exactly the wrong thing to do."

Before becoming president, Donald Trump described his future cabinet the same way he characterized his business acumen: "I'm going to surround myself only with the best and most serious people," he said to The Washington Post in 2015, two years before his inauguration. "We want top of the line professionals."

Shortly after being sworn in, Trump boasted that his generals "were going to keep us so safe."

But during his presidency, Trump's generals have slowly fell by the wayside, many of them resigning because their views were not "aligned" with his. The tepid resignation letters from these high-profile military officials evolved into a more pronounced denunciation, with some being outspoken in their opposition against Trump's policies.

Many of these former officials are Marines who served with distinction throughout the wars in Afghanistan and Iraq. The photo above, taken in 2013, marked the first time six four-star Marines Corps generals were actively serving in the Marine Corps.

Jim Mattis, the Secretary of Defense, announced his resignation in December 2018. His departure was accelerated after Trump announced his acting replacement, Patrick Shanahan, was set to take over. Mattis was a four-star general who once led the US Central Command and was celebrated as a top choice to lead the world's most powerful military. He cited disagreements with Trump's policies as the reason for his decision to resign from the Defense Department. Mattis later went on to poke fun at Trump in a light-hearted speech: "I earned my spurs on the battlefield ... And Donald Trump earned his spurs in a letter from a doctor."

the Secretary of Defense, announced his resignation in December 2018. His departure was accelerated after Trump announced his acting replacement, Patrick Shanahan, was set to take over. Mattis was a four-star general who once led the US Central Command and was celebrated as a top choice to lead the world's most powerful military. He cited disagreements with Trump's policies as the reason for his decision to resign from the Defense Department. Mattis later went on to poke fun at Trump in a light-hearted speech: "I earned my spurs on the battlefield ... And Donald Trump earned his spurs in a letter from a doctor." John Kelly, the former White House chief of staff, was a four-star Marine Corps general who once led the US Southern Command. He served as secretary of the Department of Homeland Security before being selected by Trump to regulate his day-to-day schedule. Kelly had been expected to bring order to a chaotic West Wing but faced headwinds, at times clashing with Trump. Kelly went on to describe Trump's intervention in a military court proceeding as "exactly the wrong thing to do."

the former White House chief of staff, was a four-star Marine Corps general who once led the US Southern Command. He served as secretary of the Department of Homeland Security before being selected by Trump to regulate his day-to-day schedule. Kelly had been expected to bring order to a chaotic West Wing but faced headwinds, at times clashing with Trump. Kelly went on to describe Trump's intervention in a military court proceeding as "exactly the wrong thing to do." Joseph Dunford, the chairman of the Joint Chiefs of Staff, served as the commandant of the Marine Corps and the International Security Assistance Force in Afghanistan. His term as the top commander of the US military ended September. Trump selected US Army chief of staff Gen. Mark Milley as his replacement. In August, Dunford said the military was experiencing a "politically turbulent time" during his tenure, but added that he "will not now, nor will I when I take off the uniform, make judgments about the president of the United States or the commander in chief."

the chairman of the Joint Chiefs of Staff, served as the commandant of the Marine Corps and the International Security Assistance Force in Afghanistan. His term as the top commander of the US military ended September. Trump selected US Army chief of staff Gen. Mark Milley as his replacement. In August, Dunford said the military was experiencing a "politically turbulent time" during his tenure, but added that he "will not now, nor will I when I take off the uniform, make judgments about the president of the United States or the commander in chief." John Allen, the former commander of the US-led coalition in Afghanistan, did not serve in the Trump administration. Instead, he was an outspoken critic of Trump throughout his campaign and presidency. During a speech at the Democratic National Convention, in 2016, Allen endorsed Hillary Clinton and likened Trump's presidency to a "business transaction" that conducts "illegal activities." Trump fired back at Allen through a tweet and said his fight against ISIS "failed badly."

US Army Gen. H.R. McMaster and Trump. REUTERS/Kevin Lamarque

In addition to the Marines who will have left the Trump administration, a three-star Army general, H.R. McMaster, was fired as Trump's national-security adviser in 2018. His tenure was marked by numerous reports of disagreements with Trump, who once described him as "a man of tremendous talent and tremendous experience."

McMaster replaced another US Army three-star general as national-security adviser, Gen. Michael Flynn, who was fired after it was discovered he lied to the FBI and senior White House officials about his communications with Russian officials.

Trump with Richard Spencer at the White House, July 16, 2019. Jabin Botsford/The Washington Post via Getty Images

A senior official, Navy Secretary Richard Spencer, was also fired after his apparent disagreement with Trump. Spencer, who was a Marine Corps pilot in the 1970s, was forced to resign after Trump barred the Navy SEALs from a review of a SEAL tried for war crimes.

Trump overturned a decision to demote Navy SEAL Edward Gallagher, who was convicted of posing with the corpse of a dead detainee. The lesser charge was one of seven total charges against Gallagher, including premeditated murder of an ISIS detainee.

After Gallagher was acquitted of the most serious charges, the head of the Navy SEALs decided to move forward with a review of whether Gallagher's actions were in keeping with SEAL standards. Spencer supported the review. Trump blocked it and Spencer was forced out. The Navy SEAL admiral who ordered it also is resigning.

"I don't think he really understands the full definition of a warfighter," Spencer described Trump in a CBS News interview. "A warfighter is a profession of arms. And a profession of arms has standards that they have to be held to, and they hold themselves to."

"What message does that send to the troops," Spencer added. "That you can get away with things. We have to have good order and discipline."