There are certain (specific) cases where it is correct or even a mitzvah to hate someone else. [See The following sources: Tehillim 97:10 and 139:21, Amos 5:15, Mishlei 8:13, Pesachim 113b, Sefer HaMitzvos HaGadol Mitzvas Asei 9, Sefer Yereim Mitzvah 224.]
My question is: In cases that a Jew is obligated to hate a person, is there any room to also love him or have compassion for him?
Also, is there any episode, specifically in Tanach, where the Jewish people went to war against another people and nevertheless we find that they were (correctly) empathetic or felt love or compassion for the enemy?
Edit: We do find that Moshe Rabeinu did not lead the war against Midyan because he had hakoras hatov for living there (Medresh Tanchuma). I always thought this was incredible. One person/family in Midyan (Yisro) who was ostracized and excommunicated by the other citizens hosted him for a while (and to begin with it was not li'shem shamayim since Yisro was trying to find someone to marry his daughter and no one else was willing to because of the excommunication) and Moshe will not lead the war against other people who caused thousands of the Jewish people to die and sin. Wow! The implications of this hakoras hatov for us are hard to understand (in my mind).