On the night of December 18–19, 1941, six men of Italy's Decima Flottiglia MAS rode three manned torpedoes (maiali) into the heavily defended harbor of Alexandria, Egypt. They attached timed demolition charges to the bilge keels of battleships HMS Queen Elizabeth and HMS Valiant, putting both out of action for months and temporarily ceding Mediterranean naval superiority to the Axis. A tanker and destroyer were also damaged. All six Italians were captured — their mission remains one of the most successful special operations raids of the war.

On September 18, 1944, the British submarine HMS Tradewind torpedoed the Japanese transport Jun'yō Maru off the coast of Sumatra. The ship was carrying approximately 4,200 Javanese forced laborers and 2,200 Allied POWs being transported to build a railway. More than 5,000 died in one of the highest-casualty ship sinkings by submarine in WWII. The 680 survivors were rescued by Japanese escorts and put to work on the Pekanbaru Death Railway.

On September 12, 1942, U-156 torpedoed the British troopship RMS Laconia off West Africa, then discovered the ship carried 1,800 Italian POWs in addition to British soldiers and civilians. Commander Werner Hartenstein surfaced, broadcast an uncoded rescue appeal to all Allied ships, and began picking up survivors, draping a Red Cross flag over the submarine's deck. An American B-24 bomber from Ascension Island attacked the submarine despite seeing the rescue in progress. The incident led Admiral Dönitz to issue the Laconia Order, forbidding U-boats from rescuing survivors — a policy that likely cost thousands of lives for the rest of the war.

In 1945, the OSS launched Operation Periwig, a black propaganda campaign that fabricated an entirely fictional anti-Nazi resistance movement inside Germany. They forged letters between supposed conspirators, dropped fake resistance leaflets over German cities, planted fabricated documents on dead bodies dropped by parachute, and broadcast fake underground radio transmissions. The goal was to make the Gestapo waste resources hunting for a resistance network that did not exist.

On December 24, 1944, the Belgian troopship SS Leopoldville was torpedoed by U-486 in the English Channel just five miles from Cherbourg, killing 763 American soldiers of the 66th Infantry Division. Many drowned because rescue efforts were botched — nearby ships hesitated to approach, lifeboats were mishandled, and many soldiers had never been trained to abandon ship. The US Army suppressed news of the sinking, and families were told only that their sons died 'in the European Theater.'

From 1942-1944, the USAAF and Navy developed a weapon using Mexican free-tailed bats fitted with tiny incendiary devices, intended to be released over Japanese cities where they would roost in wooden buildings and start thousands of fires simultaneously. During a test at Carlsbad Army Airfield Auxiliary Air Base in May 1943, armed bats escaped and burned down a hangar, a general's car, and several other buildings. The project was cancelled in favor of the atomic bomb.

In September 1943, fourteen men of Z Special Unit sailed the MV Krait — a former Japanese fishing vessel already in Allied possession — over 2,000 miles from Australia to Japanese-occupied Singapore. Paddling folboats into the harbor on the night of September 26, three teams placed explosive charges on Japanese shipping, sinking or damaging multiple vessels. All fourteen men returned safely to Australia on October 19, 1943. The Japanese responded with brutal reprisals on local Chinese civilians (the Double Tenth incident).

On September 19, 1940, Polish cavalry captain Witold Pilecki deliberately got himself arrested in a Warsaw roundup to be sent to Auschwitz under the false identity of Tomasz Serafiński (prisoner number 4859). Inside, he organized the ZOW underground resistance network and smuggled out intelligence reports — among the earliest detailed accounts of the Holocaust — to the Polish Home Army and Western Allies. He escaped on the night of April 26–27, 1943, later fought in the Warsaw Uprising, and was executed by Poland's communist government on May 25, 1948.

On May 3, 1945, just days before VE Day, RAF Typhoons of No. 83 Expeditionary Air Group attacked the prison fleet in Lübeck Bay, including the Cap Arcona, Thielbek, and Deutschland. Unknown to the pilots, the SS had packed the ships with thousands of concentration camp prisoners evacuated from Neuengamme. Approximately 5,000 died on Cap Arcona alone; total deaths across the fleet reached roughly 7,000 — one of the largest single-incident maritime losses of WWII.

On May 5, 1945, soldiers of the US 12th Armored Division, Wehrmacht Major Josef Gangl and his defecting troops, Austrian resistance fighters, and French VIP prisoners — including former prime ministers Paul Reynaud and Édouard Daladier — defended Castle Itter in the Austrian Alps against a 17th SS Panzergrenadier assault. Major Gangl was killed by a sniper while shielding PM Reynaud. It is one of only two known instances where Americans and Germans fought on the same side during WWII.