Civil Contract, Paperback/Georgette Heyer

Adam Deveril, the new Viscount Lynton and a hero at Salamanca, returns from the Peninsula War to find his family on the brink of ruin. It is Lord Oversley, father of Adam's first love, who introduces him to Jonathan Chaleigh, a city man of apparently unlimited wealth, but with his eyes firmly fixed on a suitable match for his only daughter.