Aspen Sends Letter Opposing Endurance Solicitation of Authorizations

Aspen Insurance Holdings Limited (“Aspen” or “Company”) (NYSE: AHL) announcedtoday that it has issued a letter to shareholders in opposition to EnduranceSpecialty Holdings Ltd. (“Endurance”) (NYSE: ENH) solicitation ofauthorizations. Aspen's Board of Directors urges shareholders to reject bothof Endurance's proposals by promptly signing, dating and returning Aspen'sBLUE revocation card and disregarding Endurance's white authorization card.Information on Aspen's response to Endurance's unsolicited offer, includinglinks to press releases, presentations, and other important documents and SECfilings are available on the Internet at http://aspen.shareholderresource.com,or on Aspen's website at http://www.aspen.co.Below is the full text of the letter to Aspen shareholders: July 21, 2014Dear Aspen Shareholder: ASPEN URGES YOU TO REJECT ENDURANCE'S AUTHORIZATION PROPOSALSEndurance Specialty Holdings Ltd. continues to pursue its inadequate offer foryour company, Aspen Insurance Holdings – an offer that has become even weakeras a result of Aspen's strong operating results and increasing book value.Endurance is engaging in wasteful and coercive legal tactics as a desperateattempt to create a false sense of urgency among Aspen shareholders and forcethrough its inadequate proposal.Consider the facts: * Aspen is delivering on a clear plan that is generating strong financial results, including approximately 9% growth in book value per share since the beginning of this year.^i * Endurance's offer – inadequate from the start – has become increasingly deficient as a result of Aspen's strong operating results. Endurance's offer is now approximately 1.1 times Aspen's book value.^ii * Endurance's stock – which makes up 60% of its offer – is a highly unattractive currency given, among other reasons, Endurance's low-quality earnings that have been significantly dependent on reserve releases. * All three of the leading, independent governance advisory firms – Institutional Shareholder Services Inc., Glass, Lewis & Co., LLC and Egan-Jones Proxy Services – recommend that Aspen shareholders REJECT both of Endurance's authorization proposals. DO NOT TO SUBMIT ANY WHITE ENDURANCE AUTHORIZATION CARDS – PLEASE SIGN, DATE AND RETURN THE BLUE REVOCATION CARD TODAYIf you have questions or need assistance revoking your authorizations for yourshares, please contact our agent Innisfree M&A Incorporated: Shareholders calltoll-free: (877) 717-3930; Banks and Brokers call collect: (212) 750-5833. Weappreciate your input and support.Sincerely yours,/s/                       /s/  Glyn Jones Chris O'KaneChairman of the Board of Chief Executive OfficerDirectors