Thorpe was 9-for-13 with 133 yards and two interceptions for the Dukes (4-5, 2-4 Colonial Athletic Association), and he added 83 yards rushing on 17 carries.
The James Madison quarterback rushed for a 42-yard touchdown to put the Dukes up 9-0 midway through the second quarter after a getting a safety earlier in the frame. Dixon Wright kicked field goals of 23 and 38 yards to put the Dukes up 15-0 with 16 seconds before halftime.
Thorpe sealed James Madison's scoring with a 31-yard pass to Scott Noble less than 5 minutes into the third.
Wide receiver Michael Brusko had 90 yards receiving and a score for the Black Bears (4-5, 3-3), and threw an 82-yard TD on his only pass attempt.