If someone refers to a battle or other conflict as aturkey shoot, they mean that one side is so much stronger or better armed than the other one that the weaker side has no chance of winning at all.
[US, informal]
Some American pilots described the experience as a turkey shoot.
turkey shoot in British English
(ˈtɜːkɪ ʃuːt)
noun
1.
an opportunity that someone can easily take advantage of
2. military
a situation in which one army or faction extensively or unfairly outshoot another
3.
a shooting competition awarding frozen turkeys as prizes