The first (大地の章 Daichi no Shō, "Chapter of the Land") and second (天空の章 Tenkū no Shō, "Chapter of the Sky") OVAs are in fact recaps of episodes 1-13 and 14-25 of the TV series, respectively, while the third one (鉄の紋章 Tetsu no Monshō, "Crest of Iron") is a spin-off that has its own storyline and different versions of the series' characters.
Recap of episodes 01-13 from the Panzer World Galient TV series.
Recap of episodes 14-25 from the Panzer World Galient TV series.
Alternative universe spin-off of the 'Panzer World Galient' TV series
