DuPont today declared victory in its proxy fight with activist investor Nelson Peltz's Trian Management as shareholders rejected his bid to win four seats on the company's 12-member board.

In one of the largest proxy battles in US history, Trian, working with Sard Verbinnen & Co., claimed DuPont was mismanaged and saddled with a bloated cost structure. Kekst & Co. and Joele Frank represented the chemical giant.

Shareholders approved each of the dozen DuPont director nominees in a victory for CEO Ellen Kullman, who said the vote shows strong support for management's "strategic vision and continued execution of our plan."

Peltz blamed the loss on DuPont doing a "better job with the press and retail shareholders who really don't understand the issues of the company."

He said the two-year battle created substantial value for all stockholders.

"Since we first invested in mid-2013, DuPont has upgraded its Board of Directors, authorized a $5 billion share buyback, begun a long-overdue cost cutting initiative, improved the design of its executive compensation program, and announced the separation of Chemours with a $4 billion return of capital. We don’t believe these actions would have happened without our involvement," Trian said in its statement.

Trian promised to continuing monitoring the performance of the 212-year-old company.

According to FactSet, a Trian victory would have made DuPont the biggest company to lose a board seat in a vote.

SardVerb CEO George Sard, principal Carissa Felger and senior associate Amanda Klein, worked Trian's attack.

Kekst, which continues as DuPont's strategic communications counselor, used Lissa Perlman, senior VP/corporate governance practice chief; managing directors Andrea Calise, Lyndsey Estin, Kathy Deveny, Jim David; and principal Anntal Silver in the proxy defense effort.

JF's managing partner Joele Frank; partners Jamie Moser, Andi Rose; and directors Aaron Palash, Adam Pollack worked DuPont's defense.