Vulwulf Snowshod is the NPC from Riften. He says:
"Lilija joined the Stormcloaks many years ago, when the first of the skirmishes broke out across Skyrim. I was so proud of her. She served as a Battle Maiden, using her healing arts to help those that fell on the battlefield. Never even lifted a blade in her life. It didn't matter. The Imperial soldiers cut her down... killed her like a dog and left her body to rot in the mud. And that's why I won't rest easy until every single Imperial soldier joins her, and Ulfric sits upon the throne of Skyrim."
In Falkreath, Solaf of Gray Pine Goods is the one. He says:
"I was once, but not any more. I was wounded in a skirmish up near Windhelm. This was years ago, mind you."
Unfortunately, none of them say how many years ago.
Also, its worth noting that General Tullius is supposed to be a replacement sent by the Empire after their prior commander(s) in Skyrim performed so poorly against Ulfric's men.