Here he was, a prime minister with the parliamentary majority to match his ambition to build a post-Brexit utopia of better infrastructure across Britain and opportunity for all over his five-year term.
Instead he finds himself fighting an invisible enemy that is tearing apart the nation's economy, society and its health. The decisions he takes as prime minister on a daily basis will help determine how many of his citizens live or die.
He will be tested like no other leader since Sir Winston Churchill was during the Second World War. How he carries the country through this crisis will define his leadership and determine his legacy.
"I think it's going to be hell," is how Sir Nicholas Soames, former Conservative MP and Churchill's grandson described the prime minister's predicament to me. "It must be horrific and he must be exhausted.
"But as my grandpa used to say 'if you have a bear in your bedroom it's not a matter of speculation' - you've just got to deal with what's facing you as well as you can."
And so far, as economic confidence has fallen through the floor and anxiety levels ratcheted up, the country has got behind their prime minister, with 59 per cent of the public saying they believed the government was handling the crisis well, according to a YouGov/Sky News poll released on Friday.
The daily press conferences he fronts, flanked by his unflappable chief medical officer Chris Whitty and Chief Scientific Adviser Sir Patrick Vallance, has become the bread and butter of a nation starving for information about this epidemic.
The scale and pace of change is bewildering and the public are clamouring for information and answers. Civil servants, health care workers, scientists, government advisers, ministers, everyone is scrambling to try to gear up for a crisis that is out-running all of us.
Mistakes will be made, information will be miscommunicated, areas that need attention will be overlooked.
And the figurehead for all of the anxiety, the suffering, the frustration, the grief, is Mr Johnson; it is a huge weight for anyone to bear.
His is a difficult line to tread. Mr Johnson must deliver the public bad news on a daily basis while also somehow trying to rally a very scared nation.
The gravity of the situation has at times been etched into his face. He looked positively ashen on Monday as he told the country the elderly would have to self-isolate and that we would all have to stop socialising and hunker down in our homes if anyone in the family had a cough or temperature.
He knows the news is only going to get more and more difficult as this disease begins to spread more widely and claim more and more lives.
You only have to look to Italy - a few weeks along the epidemic curve from us - where there have now been 4,032 deaths and over 47,000 cases.
The severity of the situation has forced him to play the role of the sombre and straight prime minister - not his natural persona. His instinct is to charm and cajole his audience. This is a politician who trades in bonhomie to disarm his detractors. His optimism helped win him a massive majority and can be a devastating political tool.
But his attempts to inject some "boosterism" into this health battle by declaring Britain could "send coronavirus packing" in twelve weeks is risky. In trying to lift his people, he is in danger of peddling false hope.
His promise to turn the tide simply doesn't match up with the reality. Official papers say clearly strict social distancing will almost certainly have to continue for six months in order not to overwhelm the NHS.
I suspect he's trying to give people some hope, a timeline they can handle when the reality of their changing lives feels overwhelming.
The nation will need Mr Johnson's optimism and belief in Britain in the coming months. But it will also need - perhaps more - a prime minister with composure and gravitas.
You only have to glance at the support measures announced on Friday to see that this is an economic and health crisis not seen in lifetimes.
The state is closing down the country, propping up businesses and paying our wages, Mr Johnson is temporarily nationalising our economy: When he won the election he did not expect to have to do that.
Like Churchill in 1940, he is leading the country through an unprecedented national emergency.
He won the power to change Britain through the ballot box, but now Boris Johnson is being forced to rewrite the rules of the economy and society on the back of a pandemic that is radically altering not just our own country but the entire world.
We are about to enter the sort of darkest hours we've not had to endure for decades. Mr Johnson will be defined on how well he leads us through.