1941, Wednesday 03 December;
They were met in the Singapore Straits by HMS Giang Bee, another small coaster taken up into naval service as an auxiliary anti-submarine patrol craft, and led through the minefields and booms up to the Naval Base. The two Dutch submarines O-19 and O-20, of the 4th Division, were modern, the biggest in their fleet, designed for general use, as opposed to just operating in coastal waters. As a result, they had long-range endurance, were deep diving, and an offensive capability of 40 mines, as well as eight torpedo tubes, in addition they were the first submarines to be equipped with a submarine snorkel that allowed them to run their diesel engines while submerged. They had both been in Dutch East Indies waters for nearly two years now, and despite some new replacements, the crews were well trained and experienced.
Sailing with them was the Zuiderkruis, A Dutch Government Marine ship, which had been converted from a cable layer into a submarine tender, equipped with a couple of 3-ton cranes, capable of refuelling and resupplying munitions, stores and food, although she lacked the repair facilities and different workshops required to overhaul or repair submarines. For defence she was equipped with a couple of Krupp 75mm/L40 AA guns, but these were needing replacement, owing to an extreme shortage of ammunition, along with four newly install WWI era 0.30 machineguns.
Their arrival was part of the pre-agreed plan for the deployment of Allied submarines, whose implementation had recently been invoked. The two submarines were joining the 4th Submarine Flotilla, coming under the operational control of the Royal Navy. They had both previously trained with Royal Naval ships, having completed a two monthly deployment, and again would be picking up a Dutch speaking RN liaison officer, to sail with them.
The Royal Navy planned to have them work with HMS Regulus, who was already on station, forming a picket line northeast of the Poulo Condore Islands, in a line starting 30 miles off the mouth of the Co Chien river, the subs spaced 20 miles apart, in a south easterly direction. They would refuel and resupply today, before leaving early tomorrow morning to join HMS Regulus, expecting to arrive by Sunday 7th.
This wasn’t something Captain Longsdon, commander of the 4th Submarine Flotilla was at all happy about, operating a submarine picket line so close to an enemy coast line was extremely dangerous, and not sustainable, but in discussions with the Naval Planning staff, it had been appreciated that Japanese convoys would hug the French Indo-China coast, and a successful intervention could have a massive impact right at the beginning of any war with Japan. Accepting that this was to be a one-off scenario, and that the submarines would then fall back to targeting tankers and supply ships, he agreed to the deployments.
HMS Rover was also earmarked for this role, but would remain on anti-submarine warfare training in the Singapore Straits for the time being. In Hong Kong HMS Rainbow had been recalled at the end of last month and replenished, before being sent to patrol off Mako Island, while HMS Regent had sailed a few days ago, and was now patrolling off Hainan Island.
The Zuiderkruis was going to tie up alongside HMS Whang Pu, the Flotilla depot ship, and transfer torpedoes, mines and other essential supplies, enabling the servicing of the Dutch submarines. She was also carrying about thirty Dutch sailors, who would be staying to receive ASDIC or signalling training within the Royal Navy establishment. They would have Zuiderkruis unloaded in the next couple of days, she was scheduled to return to Soerabaja on Monday, escorted by the Dutch minelayer HNLMS Gouden Leeuw, provided the fitting of her ASDIC had been completed. The minelayer would have to forgo ASW training, as she was desperately needed to lay new defensive minefields.
The other three Dutch divisions were also being deployed, the 2nd Div (K-XI, K-XII, & K-XIII) were ordered to patrol the Karimata Straits, between Belitung Island and Borneo, the 3rd Div (K-XIV, K-XV & K-XVI) to patrol the Makassar Straits off Tarakan, and the 1st Submarine Division to patrol south of Celebes Island, O-16 and K-XVII set sail, while K-XVIII, which was having an overhaul in Soerabaja, wouldn’t be joining them until about a week later.