THE HANOVER INSURANCE GROUP, INC. PERFORMANCE-BASED RESTRICTED STOCK UNIT AGREEMENT

Exhibit 10.3

THE HANOVER INSURANCE GROUP, INC.

PERFORMANCE-BASED RESTRICTED STOCK UNIT AGREEMENT

This Performance-Based Restricted Stock Unit Agreement (the “Agreement”) is effective as of <GRANT DATE> (the “Grant Date”) by and between The Hanover Insurance Group, Inc., a Delaware corporation (the “Company”), and <PARTICIPANT NAME> ( “Participant” or “you”). Capitalized terms used without definition herein shall have the meanings set forth in The Hanover Insurance Group 2014 Long-Term Incentive Plan (as it may be amended from time to time, the “Plan”).

P R E A M B L E

WHEREAS, pursuant to the terms of the Plan and this Agreement, the Administrator has agreed to grant to Participant a target number of performance-based Restricted Stock Units (the “PBRSUs”); and

WHEREAS, the PBRSUs will be subject to certain restrictions, the attainment of certain performance criteria and other terms and conditions as set forth in this Agreement.

NOW, THEREFORE, for and in consideration of the foregoing and the mutual covenants and promises hereinafter set forth, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

The PBRSUs will vest on the third anniversary of the Grant Date (the “Vesting Date”); provided:

The determination of (i) whether and to the extent the Corporate Goals set forth on Schedule A have been achieved, and (ii) any adjustment to the actual number of PBRSUs earned and vested, shall be in the sole and absolute discretion of the Administrator. All decisions by the Administrator shall be final and binding upon Participant. To the extent the PBRSUs are intended to qualify for the performance-based compensation exception under Section 162(m), the Agreement shall be construed and administered in accordance with Section 162(m).

As soon as reasonably practicable following the vesting of the PBRSUs, but in no event later than 60 days following vesting, the Company shall issue the Shares to Participant. Any fractional share shall be rounded down such that only whole shares are issued. In the event the Vesting Date falls on a non-business day (weekend or holiday on which banks are not generally open in the Commonwealth of Massachusetts), the Vesting Date shall be the next following business day.

If Participant ceases to receive benefits under the Company’s Long-Term Disability Program prior to becoming Disabled and immediately returns to active Employment, the PBRSUs will continue to vest in accordance with Section 2 of this Agreement.

In the event Participant is entitled to a pro-rata vesting of PBRSUs pursuant to this Section 4, the “vesting date” (for purposes of issuing the Shares), shall be the later to occur of (i) the date Participant is Disabled, or (ii) the Goal Completion Date; provided, however that such date shall not be later than the Vesting Date and in all events no later than March 15 of the year following the year in which the Goal Completion Date occurs.

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In the event Participant is entitled to a pro-rata vesting of PBRSUs pursuant to this Section 5, the “vesting date” (for purposes of issuing the Shares), shall be the later to occur of (i) Participant’s death, or (ii) the Goal Completion Date; provided, however, that such date shall not be later than March 15 of the year following the year in which the Goal Completion Date occurs.

(a) Except as provided below in Section 6(c), upon consummation of a Change in Control, to the extent the PBRSUs are outstanding immediately prior to the Change in Control, Participant shall automatically vest in such number of PBRSUs as determined in Section 6(b).

(b) No vesting pursuant to Section 6(a) shall occur if the Company does not achieve the Corporate Goals at the specified level set forth and determined in accordance with Schedule A.

(c) Notwithstanding Section 6(a), no acceleration of vesting shall occur with respect to the PBRSUs if the Administrator reasonably determines in good faith prior to the occurrence of a Change in Control that this Award of PBRSUs shall be honored or assumed, or new rights substituted therefor (such honored, assumed or substituted award hereinafter called an “Alternative Award”), by Participant’s employer (or the parent or a subsidiary of such employer) immediately following the Change in Control, provided that the Alternative Award shall be a time-based restricted stock unit award that is no longer subject to any performance-based vesting requirement, and shall also:

(i) be based on stock which is traded, or will be traded upon consummation of the Change in Control, on an established securities market;

(ii) provide such Participant (or each Participant in a class of Participants) with rights and entitlements substantially equivalent to or better than the rights, terms and conditions applicable under this Award, including, but not limited to, an identical or better time-based vesting schedule;

(iii) have substantially equivalent economic value to this Award (determined at the time of the Change in Control and based upon the number of Shares Participant would have received had the Award been accelerated pursuant to Section 6(a) above); and

(iv) have terms and conditions which provide that in the event that Participant’s employment is involuntarily terminated (other than for Cause) or Participant terminates employment for “Good Reason” (as defined below) prior to the Vesting Date, Participant shall automatically vest in 100% of the Alternative Award and any conditions on a Participant’s rights under, or any restrictions on transfer or exercisability applicable to, the vested portion of such Alternative Award shall be waived or shall lapse.

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For this purpose, “Good Reason” shall mean the occurrence of one or more of the events listed below following a Change in Control:

(x) to the extent you are a “Participant” (as that term is defined in the CIC Plan) in the Company’s Amended and Restated Employment Continuity Plan or its successor plan (the “CIC Plan”), the occurrence of any of the events enumerated under the definition of “Good Reason” applicable to Participant’s “Tier” level as set forth in the CIC Plan; or

(y) if you are not a “Participant” in the CIC Plan, the occurrence of any of the following (A) a reduction in Participant’s rate of annual base salary as in effect immediately prior to such Change in Control; (B) a reduction in Participant’s annual short-term incentive compensation plan target award opportunity (but excluding the conversion of any cash incentive arrangement into an equity incentive arrangement of commensurate value or vice versa) from that which was in effect immediately prior to such Change in Control; or (C) any requirement that you relocate to an office more than 35 miles from the facility where Participant was located immediately prior to the Change in Control.

(d) In the event a Participant believes that a “Good Reason” event has been triggered, Participant must give the Company written notice within 30 days of the occurrence of such triggering event and a proposed termination date which shall be not sooner than 60 days nor later than 90 days after the date of such notice. Such notice shall specify Participant’s basis for determining that “Good Reason” has been triggered. The Company shall have the right to cure a purported “Good Reason” within 30 days of receipt of said notice.

(e) Notwithstanding Sections 6(a) and (c) above, the Administrator may elect, in its sole discretion, exercised prior to the effective date of the Change in Control, to accelerate all of the PBRSUs.

(f) Upon vesting under Section 6 any remaining unvested PBRSUs shall be automatically cancelled and forfeited and returned to the Company for no consideration.

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(a) Participant hereby acknowledges and agrees that in the event of any breach of Section 10 of this Agreement, the Company would be irreparably harmed and could not be made whole by monetary damages. Participant accordingly agrees to waive the defense in any action for injunctive relief or specific performance that a remedy at law would be adequate and that the Company, in addition to any other remedy to which it may be entitled at law or in equity, shall be entitled to an injunction or to compel specific performance of Section 10.

(b) In addition to any other remedy to which the Company may be entitled at law or in equity (including the remedy provided in the preceding paragraph), Participant hereby acknowledges and agrees that in the event of any breach of Section 10 of this Agreement, Participant shall be required to refund to the Company the value received by Participant upon vesting of the PBRSUs; provided, however, that the Company makes any such claim, in writing, against Participant alleging a violation of Section 10 not later than two years following Participant’s termination of Employment.

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The Company makes no representations to Participant with respect to the tax treatment of any amount paid or payable pursuant to this Award. While this Award is intended to be interpreted and operated to the extent possible so that any such amounts shall be exempt from the requirements of Section 409A, in no event shall the Company be liable to Participant for or with respect to any taxes, penalties and/or interest which may be imposed upon any such amounts pursuant to Section 409A or any other federal or state tax law. To the extent that any such amount should be subject to Section 409A (or any other federal or state tax law), Participant shall bear the entire risk of any such taxes, penalties and or interest.

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IN WITNESS WHEREOF, the parties hereto have entered into this Agreement as of the Grant Date.

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