Astro King - Shoukan Yuusha dakedo Kakyuu Nintei Sareta node Maid Harem wo Tsukurimasu! - Ch. 35

[ARealCoolGuy]

Is there a reason for that girl to hate the prince, because it seems like she was controlling the mammoth and trying to kill him (or accomplished killing him, one of the two).

 

[Goldni]

need moar

 

[raddcuban]

Is there a reason for that girl to hate the prince, because it seems like she was controlling the mammoth and trying to kill him (or accomplished killing him, one of the two).

Royalty get first dibs on all summoned girls. So she's just holding a grudge because she wanted to give her first to Yoshitsune. Chapter 11 lays out her feeling on her current situation and what's going on with her internally.
The mammoth was a replica summoned by her class skill, not the actual one, so yeah, she was 100% using it to attack the prince.