Sentence Correction

Hello -

Question: "Having forfeited her severance package in order to keep the rights to her intellectual property, the employee believed that she had won a moral victory."

so i have to use "had won" in the later sentence because "having forfeited" in the first sentence or because "believed"? (why i cannot use "won" instead of "had won".
basically i'm confused with:
1. the tense i need use after the modifier "Having verb-ed"
2. what "Having verb-ed" trying to show in term of the action


Thanks.