Second London Naval Treaty

Second London Naval Treaty
Public domain · source
Name	Second London Naval Treaty
Date signed	25 March 1936
Location signed	London
Effective date	29 December 1936 (partial)
Parties	United Kingdom; United States; France; others attempted
Languages	English language; French language

Second London Naval Treaty

The Second London Naval Treaty was a 1936 international agreement among London-based naval powers aimed at limiting warship construction and armament following the Washington Naval Treaty and the London Naval Treaty (1930). Negotiated amid tensions involving the Empire of Japan, the Italian Empire, and the rise of the Nazi Party, the treaty sought to stabilize naval armaments between the United Kingdom, the United States, and the French Third Republic while responding to demands from the League of Nations and debates at the Geneva Conference.

Background and negotiation

Negotiations followed the strategic aftermath of the Washington Naval Conference, the disarmament discussions at the Geneva Disarmament Conference, and the 1930 London Naval Treaty where representatives from the United Kingdom, United States, Empire of Japan, France, and Italy attempted to codify limits on capital ship tonnage and armament. The interwar naval dialogue involved figures associated with the Royal Navy Admiralty, the United States Navy General Board, and French naval planners from the French Navy, as well as diplomats linked to the Foreign Office, the Department of State (United States), and the Ministry of Foreign Affairs (France). Rising maritime rearmament by the Imperial Japanese Navy and the Regia Marina created urgency. Negotiators referenced precedents such as the Washington Naval Treaty ratios, the London Naval Treaty (1930) definitions, and the naval limitations debates influenced by states like the Soviet Union and the Weimar Republic.

Treaty provisions

The treaty reaffirmed limits on battleship displacement and main-gun caliber first set at the Washington Naval Treaty and refined in the London Naval Treaty (1930). Delegates debated maximum gun calibers, cruiser definitions, and submarine restrictions with input from naval staffs of the Royal Navy, the United States Navy, and the French Navy. Provisions sought to cap capital ship displacement, regulate cruiser construction, and constrain submarine torpedo armament using classifications that reflected earlier language from the Washington Naval Conference instruments. The text attempted to balance the differing priorities of Prime Minister Stanley Baldwin era negotiators, Franklin D. Roosevelt administration advisers, and French statesmen influenced by the Popular Front dynamics in France.

Signatories and ratification

Principal signatories included plenipotentiaries from the United Kingdom, the United States, and the French Third Republic, with other delegations present from the Empire of Japan delegation who ultimately abstained from full agreement, and the Kingdom of Italy delegation which expressed reservations. Ratification processes moved through the Parliament of the United Kingdom, the United States Senate, and the French National Assembly, where domestic debates involved military leaders from the Admiralty, the Navy Department (United States), and the Service historique de la Défense. Political currents in the United States Congress and the Chamber of Deputies (France) influenced the timing and scope of formal acceptance.

Implementation and compliance

Implementation depended on naval construction programs overseen by the Royal Navy Board of Admiralty, the United States Navy Bureau of Construction and Repair, and the Direction du Matériel Naval of the French Navy. Compliance monitoring relied on diplomatic exchanges among the Foreign Office, the Department of State (United States), and the Ministry of Foreign Affairs (France), as well as intelligence reports from naval attachés stationed in Tokyo, Rome, and Berlin. Allegations of noncompliance centered on ship classes developed by the Imperial Japanese Navy and the Regia Marina, and on clandestine design choices attributable to firms such as Vickers-Armstrongs and Naval Construction and Armaments (France) contractors.

Impact on naval design and strategy

The treaty influenced shipbuilders in United Kingdom dockyards like Rosyth and Portsmouth, American yards such as Newport News Shipbuilding and Bethlehem Steel, and French arsenals at Brest and Toulon. Designers adapted to limits by emphasizing armor schemes, Washington Naval Treaty-era displacement ceilings, and new concepts in cruiser specialization favored by the Royal Navy and the United States Navy. Strategic doctrines debated in staff colleges including the Royal Naval College, Greenwich, the Naval War College (United States), and the École de Guerre Navale shifted toward carrier aviation as signatories reassessed the utility of battleships in light of evolving Imperial Japanese Navy carrier developments and lessons from exercises involving navies of the French Third Republic and the United Kingdom.

Collapse and legacy

The treaty's constraints eroded as the Second Italo-Ethiopian War, the remilitarization of the Rhineland, and the expansionist policies of the Empire of Japan and the Nazi Party undermined cooperative arms control. The withdrawal of compliance by the Empire of Japan and the reluctance of the Italian Empire and other capitals led to rearmament programs culminating in the naval confrontations of World War II. Nonetheless, the treaty informed interwar legal thinking in institutions such as the League of Nations and influenced postwar arrangements during the Washington Naval Treaty successor discussions and early United Nations debates on arms control. The Second London Naval Treaty's procedural and technical legacies persisted in naval architecture, diplomatic practice, and the archives of the National Archives (United Kingdom), the National Archives and Records Administration (United States), and the Service historique de la Défense.

Category:Interwar treaties Category:Naval treaties