From 1890 to 1921, we were caught up in a naval arms race with a life of its own.

During the two interwar decades our Army strength hovered around 130,000. (The British had lost nearly half that number, killed or wounded, in a single day, at the opening of the Battle of the Somme.) The Pentagon lay in the future; instead the Navy and War departments, along with the State Department, shared the mansard-roofed office building that lay directly across West Executive Avenue from the White House. Here stood the center of American power, such as it was. Within it life was very casual.

That avenue was open to the public; you could park there, in view of the Oval Office. If you were to meet the Secretary of State, he might greet you at the door. The Army’s Chief of Staff, Gen. Douglas MacArthur, had only a single aide, Maj. Dwight Eisenhower. Ike often had to go up to Capitol Hill to meet with congressmen, and MacArthur had the Army’s only limousine. Ike never got to ride in it. Instead, when heading to the Hill, he would walk down the hall, fill out a form, and receive two streetcar tokens. Then he would stand outside on Pennsylvania Avenue and wait for a trolley.

Still, while officers cherished the horses and battleships that had always been the keys to victory, advocates of air power were laying the groundwork for a new kind of warfare. Here stood another milestone for the peacetime military, for here lay the rise of technology. Gen. Billy Mitchell won headlines with his impassioned advocacy, but the Navy saw the most significant activity, as it commissioned the first aircraft carriers.

The original concept was British, with the first of the type, HMS Argus , joining the fleet two weeks before the armistice of 1918. The Washington Naval Conference went on to limit the size and tonnage of these vessels—though not because 1921 naval planners worried about carrier strikes. Rather, they were concerned that nations might build conventional fighting ships in the guise of carriers, then convert them later by mounting heavy guns.

Indeed, in both Japan and the United States, the first fleet carriers entered service thought similar conversions. The USS Lexington and Saratoga began their careers as hulls for 43,500-ton battle cruisers. Slated for scrapping as a result of the 1921 conference, they won reprieves when the government received permission to reconfigure them as carriers. As compensation Japan was allowed to convert the battle cruiser Akagi and the battleship Kaga .

It was unclear at the time just what these new ships might do, but in 1929 a leading American advocate, Rear Adm. Joseph Reeves, demonstrated that the Saratoga had the punch to knock out the Panama Canal. The canal was defended by heavy guns and land-based aircraft. Reeves ran his carrier through the night to take up position, then launched its planes for a dawn attack that caught the defenders by surprise while the Saratoga stood well out of the range of shore batteries. The umpires observing this exercise ruled that a real attack would have knocked out Miraflores Locks and disabled the canal.

The subsequent decade saw something of a replay of the naval arms race that had marked the century’s early years. In Japan Adm. Isoroku Yamamoto emerged as the outstanding advocate of naval air power. Under the strong hands of his colleagues, the rest of the Pearl Harbor attack squadron took shape: Soryu, Horyu, Shokaku, ZMZ-kaku . America’s response was at first measured; one of our earliest purpose-built carriers, the USS Yorktown , received its appropriation as part of a jobs bill, the National Industrial Recovery Act. However, we soon were seeking to match the Japanese, carrier for carrier, through regular naval appropriations. We didn’t succeed; at the outbreak of the Pacific War, Japan had a marked superiority. But we had enough to turn the tide at Midway, and after that the outcome was never in doubt.

For the Army a development of similar importance lay in the four-engine heavy bomber. The first, the B-17, came about because Boeing was down on its luck. The company had been part of a conglomerate that included United Airlines, which carried few passengers but plenty of airmail, all of it government-subsidized. In 1934 a federal law broke up this cozy arrangement, leaving Boeing to shift for itself. An Army competition for a new bomber seemed like the best opportunity in view.