From 1804 to 1806, Captains Meriwether Lewis and William Clark led 31 men and one dog in the Corps of Discovery after President Thomas Jefferson commissioned them to find a route to the Pacific Ocean through the newly acquired Louisiana Territory. Along the way, they mapped the land and recorded its resources and native peoples during a journey that lasted two years, four months, and ten days and covered over 8,000 miles. The Corps of Discovery reached the Columbia River at its confluence with the Snake River on October 16, 1805, then descended the Columbia in five dugout canoes, leaving an almost treeless desert climate and entering a landscape of lush green vegetation, including fir, spruce, ash, and alder along the riverbanks and hills. The expedition followed the Columbia the final 325 river miles to the Pacific, first noticed tidal influence at Beacon Rock, and passed the rocky bluff at today's site of St. Helens on November 4, 1805. Violent weather pinned the party along the river's banks west of St. Helens for days, and the last sixteen miles down the Columbia to the Pacific Ocean took ten days because of the bad weather. The explorers huddled among rocks and driftwood on the river's north shore in Washington for nearly three weeks before voting on November 24, 1805, to spend the winter on the south shore in Oregon. They arrived at Fort Clatsop on December 7, 1805, established winter quarters there, spent a long, dreary, wet winter, departed for home on March 23, 1806, and passed through the St. Helens area again in late March 1806.