England are now the only side who can complete a Grand Slam in 2013, after opening their campaign with contrasting victories over Scotland and Ireland.
Last week, England ran up 38 points and took their attacking game to a new level to win the Calcutta Cup. Today, under incessant rain, it was what Lancaster calls their "warrior spirit" which shone through in a game of brutal intensity.
Two years ago, when England came to the Aviva Stadium chasing a Grand Slam, they failed to match that ferocity and were blown away.
Today they met it head on. Captain Chris Robshaw led from the front to win a deserved man of the match award but he was ably supported by a team of fierce competitors.
Ireland's first attempt at their famed choked tackle failed, when Billy Twelvetrees managed to get to ground and the tacklers were penalised for not rolling away.
Farrell slotted the kick to give England a second-minute lead and in wet conditions he spent a lot of the day putting boot to ball, as did Ireland's Jonathan Sexton.
Handling was difficult and although the dropped balls made for scrappy rugby, it was no less compelling given the brutality of the breakdown battle.
Farrell was fortunate not to be sin-binned for dragging back the Ireland scrum-half Conor Murray after Craig Gilroy had charged down a clearance.
Referee Jerome Garces implored "discipline" to the two captains but this match was bubbling on the edge and tempers flared again before the interval, with Donnacha Ryan at the epicentre.
Twice Ireland attacked down the blindside through Keith Earls, who had been sent on for the injured Simon Zebo, but the hosts were struggling to retain the ball in contact.
England capitalised on that let-off with Farrell ignoring the whistles to land a second penalty after Ryan had been spotted coming in from the side.
It was a sucker punch to Ireland, who had been on top but had nothing to show for their exertions.
Ireland then lost Sexton to a hamstring injury and they could have been further behind at the interval when his replacement, Ronan O'Gara, was penalised for holding on after an excellent tackle from Joe Marler but Farrell pushed the kick wide.
The Irish scrum began to get on top after the break, winning penalties at consecutive set-pieces allowing O'Gara to kick his side onto the board.
Courtney Lawes, Manu Tuilagi and then Dylan Hartley were sent on as England sought to halt Ireland's growing momentum by upping the intensity.
James Haskell was sin-binned for kicking the ball away as he wriggled out of a ruck and O'Gara landed his second shot at goal to draw Ireland level just before the hour mark.
It was a decisive period, but not in the usual way. England were a man down but refused to go into their shells and were rewarded for it, scoring six points while Haskell was off the field.
Ben Youngs tried a little chip ahead which bounced too awkwardly for Tuilagi to gather behind the Irish try-line but England had the penalty and Farrell converted to regain the lead.
Lawes then chopped down Kearney and Brown, chasing up his own kick ahead, was straight in over the top to earn another penalty which Farrell slotted from the same position.
O'Gara was struggling to impose himself. He had already scuffed two kicks to touch when he pushed a penalty shot wide of the posts, spurning a route back into the game for Ireland.