The Tactica () is a military treatise written by or on behalf of Byzantine Emperor Leo VI the Wise in ca. 895-908 and later edited by his son, Constantine VII. Drawing on earlier authors such as Aelian, Onasander and the Strategikon of emperor Maurice, it is one of the major works on Byzantine military tactics, written on the eve of Byzantium's "age of reconquest". The original Greek title is ("short instruction of the tactics of war"). The Tactica elaborates on a wide variety of issues, such as infantry and cavalry formations, drills, siege and naval warfare etc. It is written in a legislative form of language and comprises 20 Constitutions (Diataxeis) and an Epilogue and is concluded by 12 additional chapters, the latter mainly focusing on ancient tactics.