Complex sentence: Luis de Onís (1769--1830) Born in La Mancha, Spain was the Spanish foreign minister in Washington from 1809 to 1819 and the one who negotiated the Adams-Onís Treaty with United States Secretary of State John Quincy Adams in 1819.
Split into simpler sentences: Luis de Onís (1769--1830) Born in La Mancha, Spain was the Spanish foreign minister to the United States from 1809 to 1819. He is remembered as the man who negotiated the Adams-Onís Treaty with United States Secretary of State John Quincy Adams in 1819.