THG 2019 Proxy Statement

THE HANOVER INSURANCE GROUP, INC. 440 L INCOLN S TREET W ORCESTER , M ASSACHUSETTS 01653 Letter to our Shareholders from John C. Roche, our President and Chief Executive Officer March 28, 2019 TO OUR SHAREHOLDERS: You are cordially invited to attend the Annual Meeting of Shareholders of The Hanover Insurance Group, Inc. to be held on Tuesday, May 14, 2019, at 9:00 a.m. local time, at the Company’s headquarters in Worcester, Massachusetts. The accompanying Notice and Proxy Statement describe in detail the matters to be acted on at the Annual Meeting. Your vote is important. We hope that you will vote as soon as possible. Please review the instructions concerning each of your voting options described in the accompanying Proxy Statement. Your cooperation will assure that your shares are voted and will also greatly assist us in preparing for the Annual Meeting. Sincerely, John C. Roche President and Chief Executive Officer