'De Arte Athletica' (Volume II) [B Cod.icon. 393(2)] is online at the Bavarian State Library.
The massive mid-16th century treatise on combat techniques by Paul Hector Mair totals over twelve hundred pages, spread across two exquisitely illustrated manuscripts.
Volume I - featured earlier this year in the entry Pugnacious Puffy Pants - 'tends' to concentrate more on the armed and unarmed hand-to-hand techniques, while the present volume introduces the tournament combat styles of knights.
A number of the illustrations are thought, perhaps unsurprisingly, to have been derived from or copied after the style of Hans Bergkmair (both father & son); see: Burgkmair Tournament Book. Some of the scenes and combattants depicted in 'De Arte Athletica' are based on actual tournaments (and participants) from history.