Ireland's Paul Stirling and captain Andy Balbirnie struck superb centuries as the tourists chased down a daunting target of 329 to stun world champions England with a seven-wicket win in the third and final One-Day International at the Rose Bowl on Tuesday.
England, who had already sealed the series, batted first and recovered from early trouble to post 328 all out one ball shy of their 50 overs with captain Eoin Morgan providing another classy century against the country of his birth.
But Ireland never looked intimidated in their chase as Stirling smashed 142 from 128 balls and Balbirnie 113 from 112 to put on a record 214 for the second wicket, and the second highest partnership for Ireland in ODIs as they reached their target with one ball to spare.
The series is the first in the International Cricket Council's 13-team Super League that serves as the qualifiers for the 2023 World Cup in India, where the hosts and the leading seven sides will play at the finals.
England slipped to 44-3 at the start of their innings, but Morgan, who previously played 23 ODIs for Ireland, took the attack to the bowlers and was well supported by Tom Banton (58) as they put on 146 in 18.2 overs for the fourth wicket.
David Willey (51) and Tom Curran (38 not out) added 73 more for the eighth wicket to see England past 300.
Ireland raced along in their reply, aided by a poor length from the home bowlers, with Stirling reaching his ninth ODI century and captain Balbirnie his sixth, but neither could see their side home.
The visitors needed eight off the last over bowled by Saqib Mahmood, and were aided by a waIst-high no-ball that provided an extra ball and a free hit.
Ireland's only other victory over England in 13 matches came at the 2011 World Cup when they scored 329 for seven as Kevin O'Brien scored a century.
He was at the crease to hit the winning runs in this latest victory to seal another famous Ireland success.