“More than [about] policy…, Barack Obama was about ideology and a worldview often at variance with Israel’s.” These words constitute the thesis statement of Ally: My Journey across the American-Israeli Divide, the new memoir by the historian Michael Oren, who served as Israel’s ambassador in Washington from 2009 to 2013. Given the grave urgency of the regional and international challenges facing the Jewish state, and given what is widely perceived today as a severe crisis in America-Israel relations, the book couldn’t be timelier—as the instantaneous media ruckus attending its publication amply testifies.