The body of Major-General Mackinnon now lies in St. Paul's Cathedral in London, next to his brother officer Major-General Robert Craufurd, both casualties of the assault on Cuidad Rodrigo during the Peninsular War. Mackinnon left behind his private journal filled with the details of the scenery, manners, customs and people of both Spain and Portugal as he found them during the Peninsular War, right up until his death. The journal was only intended for perusal by his closest family, but bears closer examination by those interested in the Peninsular War.