On Dec. 2, 1943, more than 100 German bombers attacked the port of Bari, Italy. In just minutes, they sank and damaged 25 Allied ships and inflicted thousands of painful injuries and deaths, most of them caused by American mustard agent. The attack was successful beyond imagination. In military circles, it became known as the second Pearl Harbor. Yet even today, it remains one of the least-known aspects of World War II.

Bari sits on the Adriatic Sea coast of Italy just above the heel of the Italian boot. Its excellent harbor was the port of choice for the shipment of vital war supplies to Italy. However, the harbor’s limited capacity to handle ships forced them to lie at anchor for days waiting to be unloaded. Luftwaffe reconnaissance flights observed the harbor’s crowded conditions and slack defenses. Field Marshal Albert Kesselring ordered his fleet of bombers to attack Bari’s harbor immediately. What Kesselring could not have known was that an American freighter, the John Harvey, was among the ships waiting to be unloaded, and the Harvey was, above all others, the perfect target.

President Franklin Roosevelt had ordered that a shipment of mustard be sent to Italy. So, the Harvey was loaded with a top-secret cargo of 100 tons of mustard in 100-pound bombs. This was secret, because using mustard would violate an international treaty banning it. Only a few high-level American officials and five chemical warfare experts on the Harvey knew it was carrying mustard.

The Luftwaffe planes swept low over the harbor, catching Bari’s lax defenses off guard. Many of the Allied ships were moored in double rows along its docks, perfectly arranged for the attack, and the German bombs smashed into the ships with great accuracy. Within minutes, 17 ships had been sunk and eight others were in flames. The crews jumped overboard to escape.

The Harvey was hit and exploded with tremendous violence when the flames reached the mustard-filled bombs in its hold. The enormous blast blew mustard liquid and gas high above the harbor. The liquid settled on the oil-covered water and the gas drifted ashore. Everyone on the ship who was aware of the secret cargo was killed in the explosion, so no warning of its presence was possible.

Mustard is a liquid; its vapors are called mustard gas. Both the liquid and the gas readily penetrate clothing and rapidly affect normally damp areas of the body. The eyes, lungs, armpits and genital areas are most quickly blistered. Bari’s hospitals were not at all prepared to deal with a chemical attack. Far more importantly, they did not realize they had undergone one.

Everyone’s attention was focused on the explosions erupting in the harbor, but mustard’s far greater threat was invisible. A deadly mixture of mustard-saturated fuel oil soaked through the clothing and covered the skin of the sailors swimming in the harbor’s water.

The recovered survivors were treated for shock, exposure and conventional burns. Not surprisingly, they did not respond to these therapies. Soon complaints of stinging eyes and burned and blistered skin were common. These symptoms of mustard poisoning puzzled the medics, since they had never seen them and were not trained in their treatment.

In the rush to care for survivors, their mustard-soaked clothing was seldom removed. This allowed the deadly chemical to continue to penetrate their skin and resulted in many deaths that might have been prevented. Finally, an American doctor spoke to some longshoremen who told him they might have previously unloaded mustard. That was the clue that eventually led to the proper treatment of the military casualties, but this vital information was never shared with the civilian physicians treating Italian casualties. It is estimated that more than 1,000 civilians died.

British Prime Minister Winston Churchill refused to admit that there were any mustard casualties at Bari. Gen. Dwight Eisenhower maintained that no other conclusion was possible. Despite this, Churchill ordered that all British records be purged of any mention of mustard. At his insistence, this position was maintained until long after the end of the war.

In an ironic twist of fate, the Bari attack contributed to advances in chemotherapy that have prolonged many lives. Inconclusive earlier work had suggested that mustard-related compounds called Nitrogen Mustards might be useful in the treatment of blood-related cancers. The attack afforded patients with damaged lymphatic systems and bone marrow upon whom Nitrogen Mustard chemotherapy could be tested. These tests clearly established its effectiveness.

We will never know how many lives have been saved as a result of the medical data obtained from Bari’s victims. We can only hope that the good that resulted from their suffering may outweigh the harm done by the “need for secrecy” that doomed so many of them.

Frank J. Dinan, who obtained his doctorate in chemistry, taught that subject at Canisius College for 45 years until retiring two years ago. Now a professor emeritus, he lives in Tonawanda.