Owen Farrell kicked England to a battling victory at the Aviva Stadium that kept alive their chances of claiming a Grand Slam.
Lancaster believes that his team showed maturity beyond their years to beat Ireland in their own backyard under difficult conditions after James Haskell was sinbinned late in the second half.
He told reporters: "I am delighted to get the win here today. When you have the conditions as they were it was going to be a tight game and down to small margins.
"To come here with a young side and show that kind of maturity to close the game out was hugely pleasing. It is a very difficult to play rugby against experienced players when we have lads on single figures in terms of caps, it is great testament to their maturity.
"As a test of character it was right up there because of the quality of the Ireland side and the ability to get the win."
England are now the only side still in with a chance of claiming a Grand Slam ahead of their next Six Nations match against France at Twickenham on Saturday, February 23.