What rank did meriwether Lewis hold in the US Army?

private is not the correct answer.

Meriwether was promoted to Captain in the United States Army in December, 1800. He was a career soldier since the age of 18 when he joined the Virginia militia to volunteer for duty during the Whiskey Rebellion in 1792. He joined the U. S. Army in 1795 and resigned his officer's commission in 1807 when he was appointed Governor of Louisiana Territory and Superintendent of Indian Affairs.