After losing the 1912 election to Woodrow Wilson (see "Campaigns and Elections" for details), Roosevelt and his son Kermit embarked on a voyage into the jungles of Brazil to explore the River of Doubt in the Amazon region. During the seven-month, 15,000-mile expedition, Roosevelt contacted malaria and suffered a serious infection after injuring his leg in a boat accident. Following his return to the United States, he spent his days writing scientific essays and history books. When World War I broke out in Europe, the former President led the cause for military preparedness, convinced that the nation should join the war effort. He was greatly disappointed in President Wilson's call for neutrality and denounced his country's inactivity. When the United States finally entered the war in 1917, he offered to organize a volunteer division but the War Department turned him down. However, all four of his sons volunteered to fight in the war. When his youngest son, Quentin, was shot down and killed while flying a mission in Germany, Roosevelt became despondent. Thereafter, although he continued to tour the nation making speeches in favor of war bonds and the war, his mood and voice were less enthusiastic. For the first time in his life, sadness overtook the once unconquerable warrior. Theodore Roosevelt died in his sleep on January 6, 1919, in his beloved house at Sagamore Hill in Oyster Bay, New York. One commentator said that death had to take him while he slept else it would have had a fight on its hands.