Book XXI of the historian’s epic work features the beginning of the Second Punic War (also known as the Hannibalic War). He sets the scene for Hannibal’s daring crossing of the Alps and subsequent invasion of Italy, complete with the panic that gripped the Romans and the men they sent forth to stop him. Walsh is in the forefront of Livian scholarship as this edition with its comprehensive commentary, filled with historical context and perspective, demonstrates. This volume (commentary but not translation, mind you; for translation there is a superb Penguin edition by Aubrey de Sélincourt) also includes a useful vocabularly listing in the back, and is excellent for any student of Livy and Latin literature.
The synopsis accompanying this book's listing cannot possibly be correct. Livy's Book 21 details the beginning of the Hannibalic War -- from Hannibal's crossing of the Ebro through his crossing of the Alps (on elephants!), and finally to his defeating the Romans at Trebia. We owe PGWalsh a wealth of gratitude for his dedication to Livy-- and for the abundant intellectual fruits of that dedication.