The modern vessels of the Royal Netherlands Navy had already departed Dutch waters by 16 May. On that day, Hr.Ms. Flores and Hr.Ms. Van Meerlant sailed for Dunkirk, leaving only a number of auxiliary craft behind.
These remaining vessels were designated BV ('Bewakingsvaartuig', or Guard Vessel). Most were armed tugs, trawlers, or requisitioned fishing boats that had been pressed into naval service. Most of these had been fitted out with a modest 3,7 cm or 5 cm gun and a few machine guns. Although modest in size and capability, they continued to perform a variety of duties in Dutch waters during the final stages of the campaign.
The fate of these auxiliary vessels is briefly described below.
Hr.Ms. Flores was a sloop-of-war and gunboat of 1,793 tons, armed with a main battery of three 150 mm guns and a AA-armament of one 7,5 cm gun and six 12,7 cm MG's. The class was designed to accommodate a reconnaissance seaplane, although this aircraft was only carried while serving in the Dutch East Indies. She had been commissioned in 1926, just like her sister ship Soemba. The two vessels of the Flores class had been specifically designed for operations in the coastal waters of the Netherlands East Indies where it would be a leading escort vessel.
During the war, Flores performed a wide variety of duties, including convoy escort and naval gunfire support missions. After reaching England later in May 1940, she served extensively in the Mediterranean and participated in many of the major Allied naval operations in that theatre. She was often accompanied by her sistership Soemba, the couple of them often being referred to as 'the terrible twins'. During the Normandy landings, she and her sistership provided fire support by bombarding German batteries and defensive positions near Arromanches and Sword Beach. She survived the war with distinction and remained in service until being stricken from the naval register in 1960. The vessel was scrapped in 1968.
Hr.Ms. Johan Maurits van Nassau, a modern gunboat with a main battery of three 150 mm guns, commissioned in 1933 and displacing around 1,600 tons, was tragically sunk by German aircraft on 14 May while en route to England. Before her loss, she had played an important role in the defence of the Kornwerderzand position on the Afsluitdijk, where her 150 mm guns successfully engaged German artillery batteries on the Friesland shore. While still close to the Dutch coast on her voyage to England, she was attacked by German dive-bombers, hit twice, and sunk. Fifteen members of her crew lost their lives.
Hr.Ms. Sumatra, an 8,000-ton light cruiser, commissioned in 1920, reached England on 11 May. She was part of the Java-class, that had been foreseen to comprise three ships, but eventually only consisted of Java and Sumatra. The class was well armed for light cruisers with ten 150 mm guns, a four gun strong 75 mm secondary battery for AA purposes assisted by six 4 cm AA guns and six 12,7 cm MG's. The cruisers were capable of carrying two Fokker C-XI-W floating-planes. Sumatra's sister ship, Hr.Ms. Java, served as flagship of the Netherlands East Indies Squadron and was sunk during the Battle of the Java Sea on 27 February 1942. Following that battle, Sumatra was the only surviving Dutch cruiser of her class. She served with several Allied naval escort formations before being laid up in November 1942 as a consequence of irrecoverable propulsion issues. Her armament was subsequently removed and used elsewhere, including for the refit of Hr.Ms. Flores. In April 1944, the vessel was recommissioned under Royal Navy control as one of the blockships intended to protect the artificial Mulberry harbours off Normandy. On 9 June 1944, she was deliberately scuttled as a breakwater.
Hr.Ms. Van Meerlant, an elderly 687-ton minelayer of the Douwe Aukes class armed with two 75 mm guns, was assigned to the Thames Local Defence Flotilla after reaching Britain. On 4 June 1941, she struck a mine in the Thames Estuary and sank with the loss of 41 crew members. Her sister ship, Hr.Ms. Douwe Aukes, had already reached the United Kingdom on 14 May 1940. In 1941 she was transferred to the Royal Navy, returning to Dutch service after the war.
Auxiliary vessels BV 33, BV 37, and BV 38 proceeded directly to England. BV 39 and the hydrographic survey vessel Hr.Ms. Hydrograaf reached Ostend on the morning of 18 May. Hydrograaf, a 397-ton survey vessel, commissioned in 1910, that had also been adapted for auxiliary minelaying duties and carried one 75 mm gun and two 12.7 mm machine guns, subsequently crossed to England escorted by the Royal Navy destroyer HMS Keith and accompanied by three civilian pilot vessels.
During the war the ship was mainly used as a lodging boat for the mine-sweeping service crews and later served as a depot ship in Harwich. It was recommissioned into Dutch service in 1944 and reinstated in the Flushing navy flotilla to survey the Western Scheldt in order to get Antwerp into operation as soon as possible. She would continue to serve the Dutch navy until 1962, when she was decommissioned and sold. She is actively used as a party boat up until this very day.
BV 31 was abandoned by her crew on the evening of 17 May after being attacked by German aircraft. The vessel later struck a mine and sank. BV 36 had been assigned to tow the heavy destroyer Hr.Ms. Philips van Almonde, a 2,240-ton vessel, then under construction at the De Schelde shipyard. Armed as designed with five 120 mm Bofors guns, four Bofors 40 mm anti-aircraft guns, eight torpedo tubes, four depth-charge throwers, and a capacity for twenty-four mines, she would have been one of the most powerful ships in the Dutch fleet. The attempt to tow the unfinished destroyer to safety failed when the vessels proved unable to pass the locks. Before Walcheren fell, Dutch forces thoroughly sabotaged and abandoned the ship. The Germans later scrapped the hull.
Her sister ship, Hr.Ms. Isaac Sweers (G83), successfully escaped to Britain and served with distinction until she was sunk by U-431 off Algiers on 13 November 1942. Two additional sister ships fell into German hands. One proved too badly damaged to complete, but the other entered service with the Kriegsmarine as ZH-1 [Zestörer Holland 1]. Heavily armed with five 120 mm Bofors guns, four Rheinmetall 37 mm anti-aircraft guns, sixteen 20 mm anti-aircraft guns, and eight torpedo tubes, she served until being sunk by British destroyers off Île de Batz on 9 June 1944.
BV 40 surrendered after her captain received news of the armistice. He judged an attempt to reach England or France too risky, citing the absence of reliable minefield charts and navigational information. He was one of the few Dutch naval officers to use such arguments to justify surrender.
The two naval training vessels, OS I and OS II, likewise surrendered to the Germans.
The militarized tug Bath I [originally tug Borneo, 1920] was heavily damaged in a German air attack while attempting to reach England. Still close to the Dutch coast, the vessel ran aground near Cadzand. Her crew abandoned ship and eventually reached England by making their way overland through France.
The story of the militarized tug Bath II [originally tug Achilles], 1921 was different. The tug lay at anchor off the west coast of Schouwen-Duiveland and when it started making steam to cross the North sea to England a mooring line got stuck on the propellor shaft. When divers were cutting the knot around the shaft, the ship suddenly received distant shell fire from French Chasseurs that took it for a German ship preparing to cross the Eastern Scheldt for Walcheren. The captain decided to abandon the ship after beaching it. Although the French ships continued the shelling nobody was injured or killed. All made a safe way out and away from the beached Bath II. It was later repaired and commissioned by the Germans.