It was 4:30 a.m. on Monday, Sept. 2, 2013, Labor Day, and Randal Milch, the general counsel of U.S. telecom giant Verizon Communications Inc., had just left the New York offices of the company’s lawyers, Wachtell, Lipton, Rosen & Katz. In a few hours’ time, Verizon was due to announce a record-breaking $130 billion deal to buy U.K. telecom company Vodafone Group Plc out of its mobile services joint venture, Verizon Wireless. There was just one problem: The deal wasn’t finished.

Back at Wachtell’s base on West 52nd Street, hordes of caffeinated lawyers frantically rushed to put the final documents together. Milch had just pulled a 12-hour overnight Sunday shift, but sleep was out of the question. Walking down 6th Avenue on the way to his Chelsea home for a quick shower and shave before heading out to New Jersey for the final pre-announcement board meeting, and with the sun still yet to rise, he called his opposite number, Vodafone general counsel Rosemary Martin, to thrash out some “fairly significant” final sticking points relating to what he would only describe as “tax issues.”