Forum:Guarding a colony - Stamina

Hi, my colony was attacked so I send some troops from capital to help. When they joined the battle, their stamina was 8.8 (right from the beginning) Why? and also, I'm interesting why stamina of attackers decreased much more slowly than on the side of defenders? There was no cook on the side of attacker. it was not the ratio between attack level and defend level but level of stamina what decided how the battle will end. Why?

Attacker: 20 Phalanx (attack 36) Defender: 10 Phalanx (defend 109.8) + 15 Phalanx from my capital

I lost the battle