• The first major Allied operation involving ships flying the Polish white-and-red ensign was the Norwegian Campaign of 1940. In the battles fought in the fjords, the destroyers Grom, Błyskawica, and Burza took part. The submarine Orzeł patrolled the Norwegian coast, while the passenger liners Batory, Sobieski, and Chrobry transported equipment and landing troops. As a result of Luftwaffe air raids, the destroyer Grom and the liner Chrobry were sunk. The submarine Orzeł disappeared without a trace under still unexplained circumstances, along with its entire crew. Polish vessels later took part in another major Allied operation—the evacuation of Allied troops from Dunkirk.
• In the following years, under intergovernmental agreements, the Polish Navy was strengthened with new ships transferred by the Royal Navy. These included the cruisers Dragon and Conrad; the destroyers Garland, Piorun, Orkan, and the escort destroyers Kujawiak, Krakowiak, and Ślązak; the submarines Jastrząb, Sokół, and Dzik, along with a number of smaller vessels.
• Polish destroyers and merchant ships took part in Allied convoys across key routes of the North and South Atlantic, the Mediterranean Sea, the North Sea, and the Arctic route to Soviet Murmansk. They fought against German ships and U-boats of the Kriegsmarine, Luftwaffe aircraft, naval mines, and the often treacherous ocean itself. Their journeys took them to ports in the United States, the Canadian port of Halifax, Iceland, British ports, Murmansk, and Arkhangelsk.
• Polish naval and merchant ships supported Allied efforts in nearly all major operations of the war—on the Mediterranean during the defense of Malta, the invasions of North Africa, Sicily, and Italy; at Dieppe; and in Operation Overlord—the Normandy landings. A dramatic engagement with the German battleship Bismarck was fought by the destroyer Piorun. A total of 50 ships of the Polish Merchant Navy participated in operations across the oceans.
• Polish sailors experienced both triumphs and sacrifices. Lost to torpedoes and bombs were the cruiser Dragon (Normandy, 1944); destroyers Grom (Narvik, 1940), Orkan (North Atlantic, 1943), and Kujawiak (Malta, 1942); and the submarines Orzeł (North Sea, 1940) and Jastrząb (Norwegian Sea, 1942). The Merchant Navy lost 15 vessels, including the modern liners Piłsudski and Chrobry.

In battles, landing operations, and convoy missions, Polish sailors often served side by side with those of the Royal Canadian Navy and Merchant Navy. Among many examples

• the destroyer ORP Burza played a key role in rescuing survivors from the Atlantic ocean liner Empress of Britain after it was bombed. For saving over 250 lives, the ship and crew received a special commendation from the Canadian Pacific Steamship Company.
• A spectacular action was undertaken by ORP Ślązak during the Allied raid on the French city of Dieppe. The ship provided shore bombardment and anti-aircraft defense, but earned lasting fame when its commanding officer disobeyed a direct order to withdraw and rescued 82 stranded Canadian soldiers from the beach—an action for which he was awarded the Distinguished Service Cross.
• Finally, the cooperation of Polish destroyers Piorun and Błyskawica with Canadian destroyers Haida and Huron within the 10th Destroyer Flotilla supported the Allied landings in Normandy. Victories in battles on the English Channel against German destroyers stand as powerful examples of Polish–Canadian wartime brotherhood.

Today, both Błyskawica and Haida stand as museum ships in Gdynia and Hamilton, bearing witness to the shared legacy of struggle and sacrifice.