The First Submarine Attack: The first successful submarine attack in WW1 occurred on September 5, 1914, when the German U-boat U-21 sank the British cruiser HMS Pathfinder.

U-Boat Menace: German submarines, known as U-boats, were a significant threat to Allied shipping. They sank over 5,000 ships during the war.

Unrestricted Submarine Warfare: Germany declared unrestricted submarine warfare in 1917, allowing U-boats to sink any ship, including civilian vessels, without warning.

Lusitania Sinking: The sinking of the RMS Lusitania by a German U-boat in 1915 killed 1,198 people and turned public opinion against Germany, influencing the United States to join the war.

Submarine Innovations: WW1 saw significant advancements in submarine technology, including improved torpedoes, better engines, and more effective periscopes.

Cramped Quarters: Submarines were small and cramped, with limited space for the crew. Sailors often slept in shifts, sharing bunks.

Limited Supplies: Submarines had limited storage for food and water, making long missions difficult. Crews often relied on canned and preserved foods.

Periscope Use: Submarines used periscopes to observe the surface while remaining submerged. This allowed them to spot enemy ships without being detected.

Silent Running: To avoid detection, submarines often ran silently, turning off engines and other noisy equipment.

Depth Charges: Enemy ships used depth charges to attack submarines. These explosive devices were dropped into the water and detonated at specific depths.

Wolfpack Tactics: German U-boats often operated in groups called wolfpacks, coordinating attacks on Allied convoys.

Convoy System: The Allies developed the convoy system, grouping ships together and providing them with naval escorts to protect against submarine attacks.

Decoy Ships: The British used Q-ships, armed merchant vessels disguised as civilian ships, to lure and attack German U-boats.

Mine Laying: Submarines also laid mines in strategic locations to disrupt enemy shipping lanes.

Submarine Nets: The Allies deployed submarine nets to protect harbors and coastal areas from U-boat attacks.

U-9's Feat: The German U-boat U-9, commanded by Otto Weddigen, sank three British cruisers in a single hour on September 22, 1914.

U-35's Record: U-35, commanded by Lothar von Arnauld de la Perière, became the most successful submarine of the war, sinking 224 ships.

HMS E11: The British submarine HMS E11, commanded by Martin Nasmith, conducted daring raids in the Sea of Marmara, sinking numerous Ottoman ships.

UC-47's Fate: The German submarine UC-47 was sunk by the British destroyer HMS Loyal in 1917, highlighting the constant danger faced by submarines.

SM UB-110: The German submarine SM UB-110 was sunk by the British destroyer HMS Garry in 1918, with only 13 survivors from the crew of 34.

Diesel Engines: Submarines used diesel engines for surface travel and battery-powered electric motors for underwater propulsion.

Torpedo Development: Torpedoes became more reliable and effective, with improved guidance systems and explosive warheads.

Hull Design: Submarine hulls were strengthened to withstand greater depths and pressures.

Communication: Submarines used radio communication to coordinate with other vessels and receive orders from command.

Sonar Beginnings: Early sonar technology, known as ASDIC, was developed to detect submarines underwater.

Blockades: Submarines were used to enforce naval blockades, cutting off enemy supply lines and resources.

Psychological Warfare: The threat of submarine attacks created fear and uncertainty among enemy forces and civilians.

Anti-Submarine Warfare: The development of anti-submarine warfare tactics and technologies became a priority for the Allies.

Post-War Treaties: The use of submarines in WW1 led to post-war treaties and agreements aimed at regulating submarine warfare.

Legacy: The lessons learned from WW1 submarine warfare influenced the design and use of submarines in future conflicts, including WW2.

Rescue Missions: Submarines sometimes conducted rescue missions, saving survivors from sunken ships.

Espionage: Submarines were used for espionage missions, gathering intelligence behind enemy lines.

Heroic Feats: Submarine crews often performed heroic feats, risking their lives to complete their missions and protect their comrades.