War between two countries. Main characters are part of military squads. Their squads accomplished many impossible missions and and earned great reputation. Also both squads have very powerful secret weapon (robot in Shirogane no Ishi: Argevollen and tank in Senjou no Valkyria: Gallian Chronicles). However time is different. Shirogane no Ishi: Argevollen is in future (not so far from nowadays, their just have primitive robots) and Senjou no Valkyria: Gallian Chronicles is in past, about WW I.
Both of these anime have mecha in in but that is not the main focus. You wont see huge battles that last 20 minutes or finale battle where the mecha fight to the death. It is way more of story line driven the people seem more real like you see in real life. These don't glorify war and focuses on the metal aspect of these characters, if you want high pace fighting this not for you.
> Both are about mechas
> The MC in both have a special mecha,that can take over the enemies
> Both have nations that fight one against the others with the mechas( Athens and Krishina in Broken Blade/Arandas and Ingelmia in Shirogane no Ishi)
> Both talk about political aspects and make a reflection about the life
That words tell everything about both anime
Alot different between both anime so i will only tell you the similar thing only :
+ MC (always) fighting in group not alone, just like real soldier in battlefield
+ Instead using super weapon or power, MC & his allies using strategy to take down the enemies
+ Character Development is steady, so you will never see one or two character become super-duper-like-god in just one episode