This set of tactical games was published by SPI.
The first two games in the series to be published, Renaissance of Infantry and Centurion, were designed by Albert A. Nofi and originally referred to as Tactical Game #13 and #14 respectively. These appeared as magazine issue games in S&T's #22 and #25.
Then the series design was given to John Young. The next two games published were Phalanx and Dark Ages and were slightly more complex while including much stricter command restraints on the players. When Armageddon was designed the powers that be at SPI decided that the players did not want the stricter command restraints so since the period represented in Armageddon was viewed to be much less documented anyway the designer eased them greatly and generally simplified the game.
Those first five games (Armageddon, Phalanx, Centurion, Dark Ages and Renaissance of Infantry) were re-designed as a more generic series called PRESTAGS which was published by SPI in 1975. The games in PRESTAGS were named Chariot, Spartan, Legion, Viking, and Yeoman.
A re-design of John Young's next and final tactical game in the series, Musket & Pike which covered 17th century tactical combat, was not included when he re-hashed the series into PRESTAGS for SPI, although the PRESTAGS Yeoman game extended only as late as the Spanish Armada.