It's important to remember that the vast majority of the ships and small craft involved in the Dunkirk evacuation were from the Royal Navy and Merchant Navy, or were manned by RN crews. Civilian volunteers made up a small proportion of the crews involved with the evacuation. That said, the evacuation force was vulnerable to air attack - the vast majority of the losses incurred during the evacuation were to air attack. However, poor training for anti-shipping strikes by the Luftwaffe, the weather, and the actions of the RAF, helped limit the total losses.

Over the course of the evacuation, the Royal Navy lost six destroyers from 41 committed to the operation. One was sunk by a U-boat, one by an E-boat, and four by bombs. Another 23 were damaged to a greater or lesser extent, all by bombs. The next most common type of ship were the minesweepers, with 36 deployed. Five were sunk, and four damaged, all by bombs. Ten trawlers from 33 were sunk, eight of which were sunk by bombs. Five of the large personnel transports were sunk by aircraft, but one was sunk by a mine. It should be clear that the majority of losses to ships committed to the operation were the result of bombing. That said, these results were worse than the Luftwaffe would achieve in the Mediterranean, or the FAA or USN would typically achieve. The Luftwaffe was poorly trained for naval operations, thanks to interservice rivalry with the Kriegsmarine. This meant that they were bad at hitting manoeuvring targets like ships in the open ocean; their best results at Dunkirk were achieved against ships in Dunkirk Harbour. On the 30th May, the weather was too poor for flying. This, of course, helped protect the ships offshore against air attack. From the 1st June til the end of the evacuation, evacuation operations were only carried out at night, thanks to the threat of air attack. Finally, the RAF committed a significant portion of the strength of 11 Group to protect the evacuation force. They mainly operated inland, intercepting bombers before they could reach the Allied bridgehead. While the RAF never managed to stop the Luftwaffe, they did help reduce the effectiveness of the raids.