War Plan Orange

War Plan Orange. It was a series of United States strategic plans developed primarily between the First and Second World Wars to address a potential conflict with the Empire of Japan. The plan, named using the Joint Army and Navy Board's color-coded system where "Orange" represented Japan, envisioned a protracted campaign across the Pacific Ocean. Its core concept involved a strategic defense of the Philippines followed by a methodical naval advance through the Central Pacific to defeat the Imperial Japanese Navy in a decisive fleet engagement. The evolving concepts within these plans profoundly influenced United States Navy doctrine and provided the essential framework for the eventual Pacific War campaign.

Background and strategic context

The origins of the plan are rooted in the geopolitical tensions following the Spanish–American War and the Russo-Japanese War, which established the United States and Japan as rival powers in the Pacific Ocean. American acquisition of the Philippines and Guam created a vulnerable strategic salient deep within Japan's sphere of influence, as recognized in the Washington Naval Treaty. Early strategic thinkers like Alfred Thayer Mahan emphasized the necessity of sea power and decisive fleet battles, concepts that became central to the plan's philosophy. The Imperial Japanese Navy's own expansion, guided by theorists such as Satō Tetsutarō, and its potential threat to Hawaii and the U.S. West Coast, made conflict planning a priority for the Joint Army and Navy Board. Rivalry over influence in China, particularly following the Open Door Policy, further exacerbated these tensions and informed the strategic context.

Development and evolution

Initial planning began informally after the Russo-Japanese War but was formally codified following the establishment of the Joint Army and Navy Board. Early versions, drafted by officers within the Navy Department's War Plans Division, were often unilateral naval concepts focusing on a rapid trans-Pacific relief of the Philippines. The War Department, concerned with the impracticality of defending distant outposts, frequently clashed with naval planners, leading to iterative revisions. Key figures in its development included Admiral William S. Sims, a proponent of aggressive naval action, and later, strategists who incorporated lessons from fleet exercises like Fleet Problem XIII. The plan evolved significantly from a simple dash to Manila Bay into a complex, multi-phase campaign acknowledging the likelihood of initial setbacks and a prolonged war of attrition.

Key assumptions and scenarios

The plan operated on several critical, and later contested, assumptions. A primary belief was that the Imperial Japanese Navy would seek a climactic Jutland-style battle near the Philippines, allowing the United States Pacific Fleet to achieve a decisive victory. Planners assumed that the United States Army could hold the fortified harbor at Manila Bay, specifically Corregidor, and the Bataan Peninsula for approximately six months until the fleet's arrival. It was also assumed that the British Empire, through its base at Singapore, and possibly the Dutch East Indies, would be benevolent neutrals or allies, securing crucial logistical lines. The scenario largely dismissed the possibility of a surprise attack on Pearl Harbor, anticipating initial Japanese operations against Guam, the Philippines, and perhaps Midway Atoll.

Major iterations and war games

The plan was rigorously tested and revised through extensive war games at the Naval War College in Newport, Rhode Island. These exercises, overseen by presidents like Admiral William S. Benson, revealed severe logistical challenges and the vulnerability of the battle fleet to submarine and aircraft attacks. Fleet Problem games in the Pacific Ocean, such as those involving the Panama Canal and Hawaiian Islands, demonstrated the difficulties of sustained fleet operations across vast distances. The controversial Joint Army and Navy Exercise No. 4 in 1932 predicted the Philippines would fall quickly, directly challenging the plan's foundational premise. These iterations gradually shifted the plan's focus from the Central Pacific to a dual advance, also considering a route through the South Pacific from bases like Samoa and Fiji.

Implementation and historical relevance

While never executed as originally conceived, the plan's strategic DNA was evident throughout the Pacific War. The surprise attack on Pearl Harbor invalidated its core assumption of an intact battle fleet, but the underlying concept of a methodical, island-hopping advance across the Central Pacific was realized in campaigns like the Gilbert and Marshall Islands campaign, the Battle of the Philippine Sea, and the Battle of Leyte Gulf. Commanders like Admiral Chester W. Nimitz and General Douglas MacArthur executed strategies that reflected decades of Orange planning, with MacArthur's New Guinea campaign echoing the southern advance variant. The plan’s emphasis on securing advanced bases, such as those at Ulithi and Saipan, and its logistical frameworks were directly implemented. Ultimately, it served as the essential intellectual and doctrinal foundation for the United States victory in the Pacific Theater, its evolution mirroring the transformation of American strategic thought in the first half of the 20th century.

Category:Military history of the United States Category:Military strategy Category:Pacific War