England coach Eddie Jones blamed himself for his team's 13-9 defeat by Ireland that ended their hopes of a second successive Six Nations grand slam and a world record 19th victory in a row.
But he said the match - and an increasingly competitive Six Nations Championship - would provide crucial lessons as the team prepare for their main goal of winning the 2019 World Cup in Japan.
England conceded an early try to Ireland lock Iain Henderson and never really threatened to get back into the match as the hosts strangled their attacking options on a windy, drizzly evening in Dublin.
All of England's points came from the boot of Owen Farrell.
"I take full responsibility for the loss today. The team didn't play well today so I've got to look at the preparation and fix it. Simple," Jones told reporters.
"They used the conditions superbly and we probably didn't."
England were already assured of this year's title but Ireland's win denies Eddie Jones' side successive back-to-back grand slam titles and the chance of setting a new record of 19 successive Test victories.
Jones said the Six Nations was likely to be significantly tougher next year and that England would have to fully take on board all the lessons they have learnt.
"We're 14 months into a four-year project. We've been chuffed with the results we've had but realism shows us we still have a lot to do," he said.
"We were caught in certain areas today and we'll learn from it and we're going to have more setbacks as we go to the World Cup."
A key skill to winning the World Cup will be coping with pressure of expectation, Jones added.
"That was like a World Cup final today and we weren't good enough," the Australian said.
"We're better off having that experience today than we are in Yokohama Stadium on November 2 (2019) at 8pm."
Ireland took the game to England at the Aviva Stadium and went ahead on nine minutes through a Johnny Sexton penalty but Owen Farrell levelled the scores eight minutes later after the home side were penalised for offside.
Continued Irish pressure on the English line resulted in the only try of the game on 24 minutes when Henderson popped off the back of the maul to score, with Sexton slotting over the resultant conversion.
Ireland failed to turn their continued dominance of the half into points and had to be satisfied going into half-time holding 10-3 lead.
England came more into the encounter in the second period and narrowed the deficit through another Farrell penalty but Ireland restored their seven-point lead on the hour mark through Sexton after the visitors were penalised for a high tackle.
Both sides exchanged further penalties to move the score to 13-9 but Ireland held firm in the final minutes, playing the final stages of the match in the England half to secure a win that seals second place in the Six Nations, a world ranking of fourth and top seeding at the next World Cup.