Forget about getting a backbone. America needs an iron constitution for the era of great power competition now upon us. So warns conservative scholar Colin Dueck in his new book, “Age of Iron: On Conservative Nationalism” (Oxford University Press, 2019). Dueck, a former “Never Trumper,” starts and ends his book with an unexpected assertion that Founding Fathers George Washington, Thomas Jefferson and the rest of the cast of “Hamilton” would have been perfectly content with President Trump’s foreign policies. What’s more, he argues, Trump policies will help 21st century America deal effectively with modern threats posed by the likes of...