This is the 13459th most frequent German word.
besiegeln
To seal, finalize, or confirm something.
In this sentence, 'besiegelten' is used in the sense of formalizing or definitively confirming a partnership through an official agreement.
Sie besiegelten ihre Partnerschaft mit einem Vertrag.
They sealed their partnership with a contract.
Here, 'besiegelt' metaphorically expresses a final, unchangeable outcome determined by an authoritative decision.
Das Schicksal des Projekts wurde durch die Entscheidung des Vorstands besiegelt.
The fate of the project was sealed by the decision of the board.
In this example, 'besiegelte' implies that the agreement definitively established and confirmed a peaceful state.