The rising young Republican politician Theodore Roosevelt unexpectedly became the 26th president of the United States in September 1901, after the assassination of William McKinley. Young and physically robust, he brought a new energy to the White House, and won a second term on his own merits in 1904. Roosevelt confronted the bitter struggle between management and labor head-on and became known as the great “trust buster” for his strenuous efforts to break up industrial combinations under the Sherman Antitrust Act. He was also a dedicated conservationist, setting aside some 200 million acres for national forests, reserves and wildlife refuges during his presidency. In the foreign policy arena, Roosevelt won a Nobel Peace Prize for his negotiations to end the Russo-Japanese War and spearheaded the beginning of construction on the Panama Canal. After leaving the White House and going on safari in Africa, he returned to politics in 1912, mounting a failed run for president at the head of a new Progressive Party.