"You were weak... and gods must be strong."
Posted by: I Em I Raptor
Against the Forerunner Military? No.
I'm going to refer to Cryptum and make an inference.
Mendicant Bias and the Flood army, full of the slowly massing/pooling infected Forerunners, attacked one of the most important worlds/meeting places of the Forerunners. With them came a Halo ring... the one Mendicant was supposed to use. With a MASSIVE Forerunner fleet inbound and Mendicant/Offensive Bias soon to commence the battle against eachother primarily, there was chaos all about. It's safe to assume that massive amounts of Forerunners got infected in this battle as they struggled out of the confusion- Especially the ones that had been trapped in the meeting area as their armor was under Mendicant's control.
With so many infected running around, the Forerunner fleet more than likely eventually met defeat- The Halos that didn't make it through the portal were likely either destroyed by the fleet or survived the fight. Assuming some survived, they were possibly, promptly infected by the Flood and the rings eventually made it to their original, predestined coordinates, awaiting the day they could be fired.
That's my on-the-spot theory.