JAFFA, Israel — The ousted French prime minister had just signed the letter authorizing the sale of a nuclear reactor to Israel — for peaceful purposes, he had been assured — even though he no longer had the authority to do so.

It was the morning after Maurice Bourgès-Maunoury’s government fell in late 1957. To get around the problem, he wrote the previous day’s date at the top of the page as an anxious Shimon Peres, then the ever-resourceful director general of Israel’s Ministry of Defense, looked on.

“I asked no questions,” Mr. Peres, who went on to serve as prime minister and president, related six decades after the event. “I said nothing at all. What was there to say?” It was, Mr. Peres said, “the most generous display of friendship I had ever known.”

The secret negotiations with the French for the reactor to be built in Dimona were one of the peaks of Mr. Peres’s long career, now distilled in his new memoir, “No Room For Small Dreams: Courage, Imagination and the Making of Modern Israel.” The book, to be published posthumously in English on Tuesday, comes a year after Mr. Peres suffered a severe stroke from which he did not recover. He died just over two weeks later, at 93.