United Continental Holdings Inc. named former Air Canada Chief Executive Officer Robert Milton chairman and made other changes to its board, settling a proxy dispute with activist investors. Milton, 55, will replace Henry Meyer III, a retired banker who took office in September after the ouster of Jeff Smisek. United also agreed to give two board seats to shareholders Altimeter Capital Management LLC and PAR Capital Management Inc., which called on the carrier to appoint a chairman with airline experience. Edward L. Shapiro, managing partner and portfolio manager at PAR, and Barney Harford, former CEO of Orbitz Worldwide, Inc., will immediately join the board, the carrier said Wednesday in a statement. The pact allows United to end a boardroom battle that threatened to overshadow CEO Oscar Munoz’s efforts to turn around the company, whose stock and operational performance have largely lagged peers since its 2010 merger with Continental Airlines. Former Continental CEO Gordon Bethune, originally the leader of the insurgent slate of candidates, won’t join the board. The hedge funds, which together hold 7.2 percent of the airline’s stock, said they weren’t trying to unseat Munoz, who has made improving labor relations a top priority. United unions representing flight attendants, ground workers, pilots and flight dispatchers have all sided with United against the activists and called their campaign a distraction. The mechanics, represented by the Teamsters, have stayed neutral.