Complex sentence: As mentioned above, in 1701, Steele published his first booklet entitled "The Christian Hero," which was written while Steele was serving in the army, and was his idea of a pamphlet of moral instruction.
Split into simpler sentences: As mentioned above, in 1701 Steele published his first booklet, entitled "The Christian Hero". Written while Steele served in the army, it expressed his idea of a pamphlet of moral instruction.