Answer:
The Gallipoli campaign was a major war operation. Stalemate basically is a situation where not a single side could win each other. So, the sentence "The gallipoli campaign became a stalemate" means the the gallipoli war operation ended up at both sides reaching a dead end and not being able to win each other.
Archetype? Symbol? Either of those could work
The reader can infer that black elks parents do not realize that he has ben on his request because B. his body never left the tepee