Intelligence gathering is an immensely complicated and vulnerable endeavor. And it often fails. Until the invention of the telegraph and radio, information often traveled no faster than a horse could ride, yet intelligence helped defeat Napoleon. In the twentieth century, photo analysts didn't recognize Germany's V-2 rockets for what they were; on the other hand, intelligence helped lead to victory over the Japanese at Midway. In Intelligence in War, John Keegan illustrates that only when paired with force has military intelligence been an effective tool, as it may one day be in besting al-Qaeda.