Prize and Cruiser Rules
There was a rule both sides followed. Before unrestricted submarine warfare became policy, there was a long-standing concept often called the “prize rules” or “cruiser rules.” In general, a warship that intended to sink a merchant vessel was expected to stop it, inspect it for contraband, and provide for the safety of the crew and passengers before sinking it.
The problem was that submarines changed the equation. A submarine that surfaced to stop a ship became extremely vulnerable. Merchant ships could be armed, could radio for help, or could even attempt to ram the submarine. As the war progressed, Germany increasingly argued that following the old rules exposed U-boats to unacceptable danger. That was one of the reasons unrestricted submarine warfare emerged.
Francis Stephens Sad Story
One of the lesser-known stories connected to the Lusitania is that of Frances Stephens, a Canadian woman whose life was touched by tragedy even after her death. She was the widow of George Washington Stephens, a prominent Canadian politician and businessman. Frances was a passenger on the Lusitania and died when the ship was torpedoed on May 7, 1915. Her body was later recovered and identified. Her family then arranged for her remains to be returned to Canada for burial beside her husband in Montreal. Her metal casket, enclosed in a wooden shipping case, was placed aboard the RMS Hesperian.
Here is where it gets unbelievable. Four months later, the RMS Hesperian was also torpedoed by the SAME U-20 and the same captain. The ship stayed afloat for a time, but sank on September 6, 1915, taking Frances Stephens and her casket down with it. That is the strange and sad part of the story. The same submarine that took her life also sank the ship carrying her home. She is still on the Hesperian to this day.
The Second Explosion: A Mystery That Remains
One of the greatest mysteries surrounding the Lusitania is the second explosion that occurred moments after the torpedo struck. Kapitänleutnant Walther Schwieger, commander of U-20, wrote in his diary that he fired only one torpedo. He also noted the second explosion and appeared surprised by it. More than a century later, historians still disagree about what caused it.
…Coal Dust Explosion
One theory suggests that coal dust inside the bunkers ignited after the torpedo exploded. Fine coal dust can be highly combustible under the right conditions. While possible, many experts believe there is little direct evidence that such an explosion would have been powerful enough to explain the damage.
…Steam Boiler Explosion
Another idea is that the torpedo damaged steam lines or boilers. However, survivors and later investigations found little evidence of a catastrophic boiler explosion. Most historians today consider this explanation unlikely.
…Secret Munitions Cargo
Perhaps the best-known theory is that the Lusitania was carrying undeclared military supplies. We now know she carried rifle cartridges, shell cases, and other war materials that were legally classified as ammunition. Some researchers believe these cargoes may have contributed to the second explosion. Others argue that the known cargo would not have produced such a massive blast by itself.
…Structural Damage
Some historians believe the torpedo caused extensive structural damage that allowed seawater to rush into vulnerable parts of the ship. As bulkheads failed and internal compartments collapsed, the sounds and shock could have been perceived as a second explosion rather than a true blast.
…So What Do Historians Believe?
There is still no universal agreement. Most researchers agree on one point: U-20 fired only one torpedo. The second explosion almost certainly originated inside the Lusitania herself, but exactly what caused it remains one of maritime history’s enduring mysteries.
Like so many famous shipwrecks, the Lusitania still has unanswered questions. Historians continue to study the evidence, but unless new information is discovered, the cause of the second explosion may remain one of the sea’s greatest mysteries.
U-20 Submarine
The vessel that sank the Lusitania was the German submarine U-20. While the Lusitania became one of the most famous ships in history, U-20 was simply one of Germany’s newest weapons. Launched in 1912 and entering service the following year, she was commanded by Kapitänleutnant Walther Schwieger, an experienced submarine officer. By 1915, Germany had begun using U-boats to attack shipping around the British Isles. The German government even placed warnings in American newspapers advising travelers that ships entering the war zone could be attacked.
On May 7, 1915, while patrolling off the southern coast of Ireland, Schwieger spotted the Lusitania and fired a single torpedo into her starboard side. Moments later, a second explosion shook the ship, something historians still debate today. Schwieger’s war diary states that he fired only one torpedo and notes the second explosion as well. Whatever caused it, the Lusitania sank in just eighteen minutes. Some historians believe it was caused by a ruptured steam line or boiler, while others point to coal dust or other factors. From Schwieger’s perspective, he had found a large British ship in a declared war zone and carried out the orders he had been given.
U-20 went on to sink a total of 37 ships, including the RMS Hesperian. Ironically, the submarine did not survive the war. In November 1916, she ran aground in heavy fog off the Danish coast and was destroyed by her own crew to prevent capture. Schwieger survived the loss of U-20 but was killed the following year when his new command, U-88, struck a British mine. One thing I find interesting is that Schwieger was not viewed by the German Navy as a rogue commander. He was carrying out his mission as he understood it. That’s one reason the Lusitania story remains so fascinating. History can look very different depending on which side of the periscope you’re standing on.
