British Prime Minister Boris Johnson described the novel coronavirus pandemic as "the single biggest crisis the world has faced in my lifetime" during a televised address to the nation on Tuesday evening.
But Johnson insists he is more certain than ever "that this is a struggle that humanity will win".
He paid tribute to those who have died and stressed "we must take action".
"I know that we can succeed because we have succeeded before," he said, adding that when the pandemic took hold in March, the country "pulled together in a spirit of national sacrifice and community".
"We followed the guidance to the letter. We stayed at home, protected the NHS, and saved thousands of lives," he said, adding that it was this action that kept the virus at bay.
However, the prime minister stressed that there have been "too many breaches".
"We have to acknowledge this is a great and freedom-loving country; and while the vast majority have complied with the rules there have been too many breaches – too many opportunities for our invisible enemy to slip through undetected," he said.
Johnson said the new measures, which include pubs, bars and restaurants closing at 10:00 pm, expanding the use of face coverings and tougher penalties for law breakers, are necessary.
The prime minister said that the risks individuals take with this virus are not their own.
"The tragic reality of having Covid is that your mild cough can be someone else's death knell," he said.
He warned that the minority who continue to flout the rules could face fines of up to 10,000 pounds ($12,700) and the army will be used to backfill the police if necessary, to enforce the new rules.
"I am deeply, spiritually reluctant to make any of these impositions, or infringe anyone's freedom, but unless we take action the risk is that we will have to go for tougher measures later, when the deaths have already mounted and we have a huge caseload of infection such as we had in the spring," he said.
He noted that if a new national lockdown came into force, it would threaten "not just jobs and livelihoods but the loving human contact on which we all depend".
But he stressed, "if people don't follow the rules we have set out, then we must reserve the right to go further."
He added: "Never in our history has our collective destiny and our collective health depended so completely on our individual behaviour. If we follow these simple rules together, we will get through this winter together. There are unquestionably difficult months to come."
He said the fight against the novel coronavirus is "by no means over" but has no doubt "that there are great days ahead".
"But now is the time for us all to summon the discipline, and the resolve, and the spirit of togetherness that will carry us through," he concludes.