Empire Conquest

Chapter 573 - 569: Advancing into the Narrow Sea

Bai Zhizhan had wanted to board the "Nanzhu Sea," but Li Mingbo and others were adamantly against it.

But this night was anything but peaceful.

Although the mine-sweeping ships had already swept the area three times and there were still a few leading the way, there didn’t seem to be a need to worry about hitting mines, Bai Zhizhan always felt that entering the Narrow Sea before capturing Jibu Fortress entailed a significant risk. An attack could happen at any time.

The key issue was that along the coast of the Narrow Sea, there were many bays where torpedo fast boats could hide.

In the southern part near the Mand Strait, there were also many isolated islands.

Frankly, it wouldn’t be a problem to conceal dozens or even hundreds of torpedo boats.

Due to the small tonnage and size of torpedo boats, which were likely camouflaged, it was possible that even if reconnaissance aircraft were sent to search during daylight, they might not be able to locate them.

And at night, this was even more so.

On the side of East Ocean, Newland’s Navy’s torpedo fast boats had caused a great deal of trouble for the Imperial Navy.

For instance, in the battle for Transfer Island, more than half of the Imperial Navy’s losses were related to Newland’s torpedo boats.

There was sufficient intelligence to confirm that the Bulan Royal Navy had long obtained the design blueprints for PT boats, and there was even a small shipyard capable of producing PT boats in Alexandria, north of the Xifan Canal. Moreover, building torpedo boats didn’t require a lot of steel, and the demands on supporting factories weren’t high.

As for torpedoes, that was even less of an issue for the Bulan Royal Navy.

From a defensive perspective, the Bulan Royal Navy had reason to deploy torpedo boats in the Narrow Sea and utilize them as the main platform for combat.

If the Alliance Group had already completed the integration of their military forces and achieved unified command, then there might also be Newland’s Navy torpedo boats hiding in the Narrow Sea.

Moreover, there was also the concern about Bulan’s Royal Navy’s submarines.

Although the Bulan Kingdom was the first victim of unrestricted submarine warfare, the Bulan Royal Navy placed great emphasis on anti-submarine measures. But that didn’t mean the Bulan Royal Navy’s submarines were lousy, nor did it mean that the Bulan Royal Navy would neglect submarines due to noble sentiments.

To be frank, they just never had an appropriate opportunity to perform.

In the Land Heart Sea, there were at least 20 submarines belonging to the Bulan Royal Navy, all of which were small and very suitable for close-to-shore activities.

Before this, these submarines were mainly used to monitor the blockade of major ports of the Raleigh Kingdom, especially military ports.

Although few in number and even fewer in opportunities, the results they achieved were quite astonishing—they sank numerous Raleigh Navy’s large warships and a great number of transport ships. Especially after Malta was occupied by the Tiaoman army, these submarines became very active.

The reluctance of the Raleigh Navy to dispatch their fleet for naval battles wasn’t unrelated to these Bulan submarines.

Furthermore, the fact that Tiaoman’s army had not reinforced Malta, especially in terms of deploying air defense units, and the inability to assure even the shipment of ammunition and supplies, were also related to the blockade of sea transportation routes.

Obviously, sending a few submarines to the Narrow Sea wouldn’t be a problem at all.

Let alone a few, even if there was just one submarine that quietly approached the fleet and seized the opportunity to launch torpedoes, it might well sink two large carriers.

In a narrow body of water, the Special Mixed Fleet couldn’t possibly spread out.

These worries of Bai Zhizhan’s were also largely related to his lack of clarity about anti-submarine warfare and his mistrust in modern anti-submarine weapons.

Yes, that’s the sonar mentioned earlier.

Although initially, the Imperial Navy developed sonar to improve the efficiency of mine-clearing, specifically to clear bottom mines and anchor mines, with the outbreak of the great war and the rise in submarine threats, the Imperial Navy discovered that sonar could also be used to detect submarines.

Indeed, it was the only effective means of detection.

Before that, anti-submarine warships could only search for submarines through hydrophones.

Because of passive detection, there were a lot of problems.

Once a submarine was discovered, at most they could roughly determine the submarine’s bearing, that is the direction it was in. Even later, using the principles of radio monitoring stations for positioning, simultaneously using two hydrophones, and determining the submarine’s position through detection angles, required being close enough.

Moreover, sound waves would reflect off the seabed and surface, causing interference with the hydrophones.

That’s why, in the era that relied on hydrophones, anti-submarine warships primarily depended on the advantage of endurance, staying in the regions where submarines frequented, waiting until the submarines ran out of electrical power or oxygen, forcing them to surface for recharging and air replenishment, and then using naval guns or deep water bombs to sink the submarines.

For this reason, anti-submarine warfare often turned into a contest of endurance.

Besides, it also required a bit of luck.

Sometimes, even after lying in wait for 2 to 3 days, it could still be in vain.

For anti-submarine warfare that focused on escorting, this method was obviously not feasible; it was impossible to leave an anti-submarine warship to guard a spot simply because an underwater object resembling a submarine was detected.

Not until the advent of sonar did the situation in anti-submarine warfare start to change.

The key was that sonar could accurately lock onto a submarine, allowing the anti-submarine warships to know where to fire, greatly increasing the hit rate of the depth charges.

According to the tests conducted by the Empire’s Navy, sonar increased the attack efficiency of anti-submarine destroyers by 20 times!

That’s why, starting from the beginning of the year, the Empire’s Navy gradually equipped anti-submarine warships with sonar, using opportunities for rest and maintenance to organize training for captains and other key officers in the skills required. Starting this year, the Naval Academy also established related courses, specifically responsible for training sonar operators.

Of course, the Empire’s Navy had more anti-submarine weapons than just sonar.

Along with sonar, what was also delivered to the Navy and played a role in anti-submarine warfare were rocket-propelled depth charges.

With rocket propulsion, depth charges for the first time had the capability for long-range attacks, allowing anti-submarine warships to fire at submarines from several kilometers away, no longer needing to sail right above the submarine to drop the bombs, thereby making more efficient use of sonar.

Besides, to increase the bombarding density, the Empire’s Navy developed a specialized launcher.

Actually, it was inspired by the Army’s rocket artillery.

Simply put, they combined multiple launch tubes, to barrage target areas with a large quantity of depth charges, increasing the hit rate by increasing the bombardment density.

You could also call it saturation striking.

Different from rocket artillery, the launch tubes were not parallel, but angled to ensure that the deployed depth charges covered the entire sea area.

Now, they also adapted submunitions, meaning one rocket carried several, or even dozens of small deep water bombs.

This idea actually came from a bold hypothesis.

The submarines that returned after being damaged almost all suffered heavy damage, losing their ability to dive, while there were hardly any that came back with minor damage. A young staff officer from the submarine forces proposed that the unreturned submarines were all sunk in battle, thus making the ignored minor damages even more deadly.

That’s how the tiny cluster depth charge came to be, with a single warhead weighing 50 kilograms and a charge of only 8 kilograms.

Being lighter and smaller, it allowed for an increase by several times in the number of dropped bombs for the same weight, effectively expanding the covered area by several times.

Later on, the Empire’s Navy developed a magnetic induction proximity fuze, allowing the depth charges to detonate near the submarine, eliminating the need for direct hits or pre-determined detonation depths before firing, not only improving operational efficiency but also significantly increasing the hit rate.

Of course, even if using hydrostatic fuzes, rocket-assisted cluster depth charges were also extremely threatening.

The Empire’s Navy was forced into this, as the threat from Newland’s submarines was simply too great, compelling the Empire’s Navy to vigorously develop anti-submarine technology.

It was with these anti-submarine weapons that the empire gained the capability to enter the Narrow Sea.