Case 738: Documentation of the Ia-unsign of the command of the II Army Corps: a description of the operation "Sea Lion", the distribution of combat tasks to the naval forces in the operation "Sea Lion", instructions, etc.

Brief Summary of Case 738

Case 738 is a collection of German intelligence reports on Gibraltar (code name “Basta”) compiled between August and October 1940, together with related operational documents. The file was assembled for planning the proposed German assault on Gibraltar and focuses on the fortress's defences, tunnels, utilities, garrison, artillery, anti-aircraft systems, and infrastructure. 

Key Contents

1. Detailed Intelligence on Gibraltar's Defences

The file contains extensive reports from agents, informants, deserters, and reconnaissance sources describing:

• northern land defences,
• walls and gates,
• anti-tank obstacles,
• minefields,
• wire entanglements,
• machine-gun positions,
• anti-tank guns,
• fortified trenches,
• defensive galleries and tunnels.

These reports pay particular attention to the approaches from Spain and the heavily fortified northern front.

2. The Tunnel and Gallery System

A major part of the file is devoted to Gibraltar's underground infrastructure.

German intelligence identified:

• tunnel entrances,
• underground halls,
• ammunition depots,
• telegraph facilities,
• fuel-storage areas,
• underground rail links,
• water and power systems,
• gallery networks connecting defensive positions.

Several reports describe large underground chambers thought to be used for communications, storage, and troop movement.

3. Artillery and Anti-Aircraft Defences

The file contains detailed estimates of Gibraltar's artillery system, including:

• coastal batteries,
• heavy fortress artillery,
• railway-mounted guns,
• anti-aircraft batteries,
• searchlights,
• observation stations,
• machine-gun defences.

Specific batteries around:

• O'Hara,
• Lord Airey's,
• Breakneck,
• Spur,
• Buffadero,
• Princess Caroline,
• Toby,
• Devil's Gap,

are identified and assessed.

4. Garrison Estimates

German intelligence estimated the garrison at roughly 10,000-11,000 personnel, including:

• infantry battalions,
• fortress engineers,
• artillery units,
• anti-aircraft troops,
• support services,
• police and administrative personnel.

The reports also discuss tanks, anti-tank guns, and recently arrived reinforcements.

5. Water, Power, Communications, and Logistics

The file includes a detailed study of Gibraltar's infrastructure:

• water reservoirs,
• distillation plants,
• rainwater collection systems,
• gasworks,
• power stations,
• transformers,
• underground power networks,
• radio stations,
• telephone and telegraph systems,
• submarine communications cables

German planners clearly regarded these facilities as strategically important and worthy of special attention during any attack. 

6. Fortification Improvements

Many reports note that British forces were actively strengthening Gibraltar's defences by:

• demolishing buildings to create fields of fire,
• constructing new bunkers,
• expanding galleries,
• adding minefields,
• reinforcing barriers,
• enlarging anti-tank obstacles,
• improving defensive positions around the lagoon, airfield, and fortress entrances.

Overall Assessment

Case 738 is essentially a German intelligence dossier on Gibraltar's military infrastructure. Unlike the operational planning files that focus on how to attack Gibraltar, this volume concentrates on understanding the fortress itself, providing detailed assessments of its defences, tunnel network, artillery, communications systems, utilities, and garrison. It demonstrates the depth of German intelligence-gathering undertaken in preparation for the proposed Gibraltar operation of 1940.