The first two episodes are summaries of the TV series, the third one (Crest of Iron) takes place in an alternate universe.

In C.E.75, the fighting still continues. There are independence movements, and aggression by Blue Cosmos... In order to calm the situation, a global peace monitoring agency called COMPASS is established, with Lacus as its first president. As members of COMPASS, Kira and his comrades intervene into various regional battles. Then a newly established nation called Foundation proposes a joint operation against a Blue Cosmos stronghold. (Source: sugoi.co)

Set in a far flung medieval-looking world of Arst, Prince Jordy Volder takes up the fight against the ambitions of the conqueror Marder. Jordy uses the legendary giant robot panzer Galient, which is one of many panzers that have been preserved underground for thousands of years. Using an army of advanced robot panzers, Marder is conquering all of Arst in preparation of his plan for dominance of the Crescent Galaxy. (Source: Wikipedia)

As the sole survivor from a squad that was sacrificed and hung out as scapegoats for embezzlement of military resources at the end of the 100 years war, Mellowlink Arity is out for revenge. Carrying the dogtags of his deceased comrades and armed with a dated AT rifle, he swears to hunt down and exact revenge on the corrupt officers that betrayed his squad, and maybe even uncover the truth behind the plot as well.