G. A. Henty 
March on London [PDF ebook] 

Young Edgar Ormskirk was born into a family of wealth in fourteenth-century England, and despite the death of his mother when he was but an infant, he grew up in a privileged but somewhat sheltered environment. When social unrest unleashes chaos in the streets of London, Edgar has to choose between the reclusive life of a scholar and the danger of the battlefield.