"Matěj slíbil, že se Rusku pomstí."

Translation: Matěj promised that he would retaliate against Russia.

[iyoossaev]

Again, all dictionaries and examples suggest this only means to take revenge, not retaliate.

[VladaFu]

take revenge is accepted

[marulin3]

Proc je would a ne will ?

[VladaFu]

souslednost časová (slíbil v minulosti)