What were the main achievements, both short-term and long-term, of Offa (b.757-796) and Alfred the Great (b.849-899)?

Both Offa of Mercia and Alfred the Great have left their imprints on the history of the English people - despite years of turmoil and darkness - leaving behind rays of enlightenment and civilized progress. Offa of Mercia (757-796), a contemporary of Charlemagne (768-814), is credited with introducing the silver penny to England. The silver penny of 793-796AD was "minted in Canterbury by the moneyer Baba". For about two centuries before Offa's reign, the main currency/coinage were smaller coins, replicas of Roman/Byzantine coins with Celtic-Germanic symbols. King Offa changed all that - th…