The 120 documents were found at Ormesby Hall, Middlesbrough and had been sent to Mary Pennyman, whose family then owned the property.
She wrote back to the women, offering words of comfort and advice.
Teesside University has received a grant of Â£9,700 from the Heritage Lottery Fund to help make the letters available online to the public.
"Researching the lives of the women who wrote [the letters] is a wonderful opportunity to reflect upon the cost of war and to build a picture of the challenges faced at the time and the strength it took to survive.
"Many commemorative projects focus on the dead but this one will focus on those who had to live on," said Dr Roisin Higgins, senior history lecturer at Teesside University, who is leading the project.
One letter sent to Mrs Pennyman was sent by Bessie Walker, whose husband was killed six weeks after they got married.
"I try to be a comfort to his poor old dad and mother.
"Sometimes wish I could be old with them, as life feels rather empty at times," she wrote in the letter.
Ivor Crowther, head of Heritage Lottery Fund North East, said: "The Pennyman letters are an extraordinary discovery and provide an incredibly personal insight into the ultimate cost of the First World War."
The letters are being stored in Teesside Archives and the project to digitise and put the letters online for the public to see is expected to take three years.
Letters sent from women whose loved ones died in World War One have been rediscovered and will be digitised.