The Horsman of war takes pleasure in causing war. He would ride into a city dressed as a member of another city and eliminate someone important or destroy an important building causing that city to declare war on the accused city. Then he would ride into the other city and do the same thing or he would come up with new and inventive way's to start wars like practicing "Dark" magic or paying bandits to raid a country etc. but he mostenjoys causing it through combat itself.
The Horsman's only purpose is to create War's domain so his master can be more powerful and have some entertainment should he wish it. Other than that he has no consious thought or the power to make his own desisions, he is a slave to War but he enjoy's the chaos he causes.