Complex sentence: Amid the growing rancor between Frick and Carnegie, Leishman attempted to steer a middle course until he retired from Carnegie service in June 1897, to accept appointment by President William McKinley, as United States Ambassador to Switzerland.
Split into simpler sentences: Amid the growing rancor between Frick and Carnegie, Leishman attempted to steer a middle course. Under pressure from both men, Leishman withdrew from Carnegie service in June 1897, to accept the appointment by President William McKinley as United States Ambassador to Switzerland.