With a couple of minutes remaining the Scots were 18-13 down in the Stadio Sergio Lanfranchi and their hopes of going to the showpiece event in New Zealand next year were disappearing fast.
However, they kept on plugging away and they got their reward when full-back Chloe Rollie scored a great try in the 79th minute and then replacement Sarah Law held her nerve to kick the conversion to give them a 20-18 victory.
Italy had beaten Spain 34-10 earlier in the day and they topped the European qualification group and are going to the World Cup.
Scotland finished second and will now play in a repechage event with Samoa, Columbia and a team from Asia to determine who will make it through to New Zealand.
We still do not know when that repechage event will be, but Easson said: “We will think about that soon, but for now I just want to praise the grit and determination these players showed in those last few minutes.
“There was a turning point in the game when we turned over the ball in our own half when Ireland were 18-13 up and you could see our energy levels going up at that point.
“We knew we’d get another opportunity and we took it when it came.
“The belief in this group has been building up and up over the last two years and I very proud.”
Ireland tighthead prop Linda Djougang gave her side a 5-0 lead in the first quarter with an unconverted try, but then back-row Edel McMahon was yellow carded and a penalty from Scotland stand-off Helen Nelson reduced the arrears.
Two minutes before half-time winger Rhona Lloyd went in for an unconverted try and the Scots were 8-5 up at the interval.
A further unconverted try from hooker Lana Skeldon made that 13-5 before the Irish fightback, indeed they scored 13 unanswered points before the quite amazing finale.