The record-breaking $43 billion acquisition of Swiss agrochemical giant Syngenta AG by Chinese state-owned China National Chemical Corp. was a case study of corporate persistence and diplomacy.

In order to pull off the landmark all-cash deal—the largest ever outbound acquisition by a Chinese company—ChemChina had to win over a reluctant seller, which had just fought off a series of hostile bids from United States rival Monsanto Co., and agree to a series of unprecedented concessions over Syngenta’s future governance.