Complex sentence: He edited the "Christian Observer" which helped fight for the abolition of the slave trade, 1802--1816 and founded The "Anti-Slavery Reporter" in 1825 and was its first editor.
Split into simpler sentences: He edited the "Christian Observer" which helped fight for the abolition of the slave trade, 1802-1816. He founded The Anti-Slavery Reporter in 1825 and was its first editor.