When President Donald Trump decided last year to hire Texas oilman Rex Tillerson as his secretary of state, the Washington foreign policy establishment thought it knew what to expect.
After all, the then 64-year-old engineer had been chief executive of ExxonMobil, the US oil giant, and so close to Russia's Vladimir Putin that he had received a medal of friendship.
He was expected to share Trump's affection for Moscow and hostility to the Paris climate change accord, and thought capable of cutting costs and streamlining his unwieldy department.
The perfect Trump man, in other words, a player from the world of business brought in to shake up or smash the Washington bureaucracy and the international order under an "America First" banner.
What Trump got, to his evident frustration, was a stubborn diplomat in a more orthodox conservative tradition, keen to reassure allies, work with the US military and hold Russia at arm's length.
Tillerson was almost immediately drawn into conflict with the White House even as he attempted to staff his department.
When he tried to enlist Republican veterans of previous State Departments, the White House barred all those suspected of having opposed Trump during his seizure of the party.
But when Tillerson sought to promote from inside the department among career officials whose work he respected, that too was vetoed for fear "holdovers" from Barack Obama's administration would be disloyal.
Now, a year on, the man who managed the world's biggest oil company has failed to staff his department, with more than 70 senior posts and ambassadorships unfilled.
Tillerson, an Eagle Scout and former national president of the Boy Scouts movement, had a very different personal and moral persona to that of his flamboyant and unrestrained boss.
Last week, he described his motivation for joining public service when he could have retired with several hundred million dollars and rode the range on his beloved Texas ranch.
Before an audience at George Mason University, Tillerson described how when he was 18 he registered for the draft to fight in Vietnam but his number in the lottery system was 89 and the recruiters only got to 86.
"And so I stayed in college, got a great education, got hired by a great company, had 41-and-a-half wonderful years," he said.
"My father is a veteran, World War II, fought in the war in the Pacific. My uncle is a retired major in the Army, did three tours of duty in Vietnam," he said.
"And as I reflected on things at that point, I said I hadn't really done anything yet. It's my time to serve, and that's why I'm doing it."
But if his motives were admirable, his results were not what he hoped for.
State Department employees were initially relieved not to have been placed under an inexperienced nationalist from the wilder shores of Trump's insurgent campaign, but were soon disappointed.
Tillerson spoke of respect and shared endeavor, but made it clear he intended to make good on the administration's plan to cut 30 percent or more from the department's budget.
Even Republican lawmakers balked at such a hack and burn policy, and retiring diplomats fed a wave of stories lamenting a "hollowing out" of the prestigious agency.
But while Tillerson's public championing of Trump's "America First" agenda cost him support from his own staff, he never really built up a bond with the commander-in-chief himself.
Though never publicly disloyal, he made known his disapproval of Trump's sympathy for racist extremists after a protest in Charlottesville, Virginia turned deadly.
And, surely most devastatingly for the thin-skinned Trump, Tillerson was reported to have referred to him as a "moron" after a national security meeting.
Tillerson apologised, but never fully denied uttering the word.
The secretary rode out months of reports his job was on the line. These became so common they were filed under the title "Rexit Rumors" by a diplomatic press corps that Tillerson never deigned to court.
But the frustration was just under the surface.
When Tillerson told reporters in China last year he had opened covert diplomatic channels to North Korea, Trump tweeted that he was "wasting his time."
In February, when the secretary was in Mexico to discuss cooperating in the war on drugs, Trump accused Latin American leaders of corruption and laxity.
On that trip, an aide to Tillerson let slip that Trump's comments were "not helpful" -- and White House officials began stirring the Rexit rumors once again.
So Tuesday's decision was not a surprise, even if the timing was brutal and apparently made without warning.
Tillerson will not leave much of a diplomatic legacy.
The man who once negotiated a historic oil deal giving his US firm access to Russia's Arctic reserves left with US-Russia ties at a historic low, a day after slamming likely Russian involvement in a poison attack in Britain in his most blistering anti-Moscow statement to date.
And the internationalist who argued with Trump that Washington should stand by allies in supporting the Iran nuclear deal steps down knowing his successor will probably tear it up.
Talks with North Korea on nuclear disarmament will likely go ahead, but not because of Tillerson's patient back channel diplomacy. Instead, they may happen because of a gut instinct decision by Trump.
US diplomats may be nervous about the plans of former CIA director and Trump confidant Mike Pompeo as he takes the State Department helm, but their taciturn outgoing boss will not be long mourned.
Born in Wichita Falls, Texas, Tillerson joined ExxonMobil in 1975 as a young engineer fresh out of college, steadily rising through the ranks to become CEO in 2006.
The silver-haired married father of four had been due to retire in March 2017, when he got Trump's call.