England coach Eddie Jones said he took "full responsibility" for a 13-9 defeat by Ireland in Dublin on Saturday that stopped his Six Nations champions from rewriting the record books.
Had England triumphed at a rainswept Lansdowne Road, they would have set a new record of 19 successive Test wins by a leading rugby union nation and become the first team in the Six Nations era to complete back-to-back Grand Slams.
But they couldn't find a way past a resolute Ireland, who finished runners-up to already crowned Six Nations champions England on points difference.
Ireland lock Iain Henderson forced his way over for the only try of the match in the 24th minute, with fly-half Jonathan Sexton several times hit by late tackles, kicking the remainder of the hosts' points.
All England, who ran in seven tries in their title-clinching 61-21 thrashing of Scotland at Twickenham last week, could manage in reply were three Owen Farrell penalties.
It was their first defeat in 18 Tests under Jones and the Australian said: "I'm disappointed and I take full responsibility for the loss today.
"I didn’t prepare the team well...I am not sure (what he did wrong). I am like everyone else and I make mistakes.
"We’re all human beings and we’re not perfect and that’s why world records finish at 18 games or 17 games.
"They (Ireland) used the conditions superbly and we probably didn’t."
However, Jones -- who has revitalised England's fortunes following their first-round exit on home soil at the 2015 World Cup -- was generally happy with the team's overall position.
Asked what he'd told his side at full-time, Jones replied: "Be proud of yourselves boys. We are Six Nations champions, back-to-back which is a fantastic achievement. We’re joint world record-holders, but we weren’t good enough today."
Jones, however, has always insisted his over-arching goal with England is to win the 2019 World Cup in Japan.
"We are 14 months into a four-year project as I have been saying.
"We have been chuffed with the results we have had but realism tells us we have still got a lot to do."
- 'Good batting average' -
The lifelong cricket fan added: "How many teams have a 90 percent winning record at Test level?
"There are not too many, the All Blacks are the only ones and we have been doing that since the last World Cup.
“We are batting at a pretty good average -– even Don Bradman got zero when he played his last Test."
Ireland lost Jamie Heaslip to an ankle injury in the warm-up but replacement back-row Peter O'Mahony led a superb defensive display.
Victory came on the back of a 22-9 loss to Wales in Cardiff last week that scuppered Ireland's title hopes.
It also meant Ireland had again stopped a winning run in its tracks following their 40-29 defeat of world champions New Zealand in Chicago in November that kept the All Blacks at 18 victories in a row.
"We didn’t necessarily talk about spoiling parties, we talked about producing performances that we could be proud of," said Ireland captain Rory Best.
Meanwhile Ireland coach Joe Schmidt paid tribute to the visitors' achievements by saying: "To be fair to England what an incredible Test match record -- 18 consecutive Test match victories.
"Winning one game is hard enough let alone 18," the New Zealander added.
"You couldn’t say anything other than they were deserved champions."
Meanwhile Best, who labelled Sexton a "real warrior", downplayed talk of deliberate late hits on the playmaker by saying: "I don’t think it was anything other than trying to put pressure on Johnny."