Morton landed with Warwick at Dartmouth on the 13th of September 1470, but the battle of Tewkesbury finally shattered the Lancastrian hopes, and Morton made his peace with Edward IV., probably through the mediation of Archbishop Bourchier.
In March 1473 Morton was made Master of the Rolls, and Edward found employment for his diplomatic talents; he was sent on a mission to Hungary in 1474, and was one of the negotiators of the Treaty of Pecquigny in 1475.
Here Morton encouraged Buckingham's designs against Richard, and put him into communication with the queen dowager, Elizabeth Woodville, and with Henry Tudor, earl of Richmond.
Morton became his principal adviser.
Morton no doubt impressed Lancastrian traditions upon Henry VII., but he cannot be credited with any great originality as a statesman, and Henry's policy was as much Yorkist as Lancastrian.