A Ring of Grass — William Ellis

Edward Talbot has always loved Sophie Trevelyan, but when in the early summer of 1914 he naively introduced her to Rupert von Laurenz, a young German naval officer, he foresaw nothing of the fateful consequences of his action. For Sophie and Rupert fall in love, and despite the imminence of war in Europe and concerted opposition from Sophie's family, they contrive a secret, idyllic love affair. However, the consequences prove far more complex, more shot with tragedy than any had contemplated.