Saint George for England by G. A. Henty

Historical novel set in the 14th century, during the Hundred Years War between England and France. The Preface begins: You may be told perhaps that there is no good to be obtained from tales of fighting and bloodshed, - that there is no moral to be drawn from such histories. Believe it not. War has its lessons as well as Peace. You will learn from tales like this that determination and enthusiasm can accomplish marvels, that true courage is generally accompanied by magnanimity and gentleness, and that if not in itself the very highest of virtues, it is the parent of almost all the others, since but few of them can be practised without it. The courage of our forefathers has created the greatest empire in the world around a small and in itself insignificant island; if this empire is ever lost, it will be by the cowardice of their descendants. According to Wikipedia: George Alfred Henty (8 December 1832 - 16 November 1902), referred to as G. A. Henty, was a prolific English novelist, special correspondent, and Imperialist born in Trumpington, Cambridgeshire, England. He is best known for his historical adventure stories that were popular in the late 19th century. His works include Out on the Pampas (1871), The Young Buglers (1880), With Clive in India (1884) and Wulf the Saxon (1895).