Battle of San Ramon Bay

The Battle of San Ramon Bay took place on 7 May 1935 between Gothian forces in Innominada and the forces of the Greater Menghean Empire. It was the first major naval engagement of the Pan-Septentrion War, part of a Menghean surprise attack against Gothian forces. It ended with a decisive victory for Menghe, allowing the Imperial Menghean Navy to operate freely off the coast of Innominada for the next several years.

Background

Geography

On the eve of the Pan-Septentrion War, Gothia had only two major naval bases in the Innominadan peninsula: Fort Fernandez, outside Rosario in the southwest, and Puerto Alegre in the southeast. This was partly a result of geography: most of Innominada's coast is made up of flat beaches and shallow lagoons, with relatively shallow water stretching out to sea. Several other cities, like Cargagena and Granada, had dredged canals and built breakwaters to allow larger ships to dock, but only these two bases had the depth, the capacity, and the security to support a large fleet comprised of multiple capital ships.

This was also a result of politics. Under the terms of the Selkiö Naval Treaty, signatories were forbidden from building or expanding naval bases and fortifications in their overseas colonies, possessions, and dependencies. Though nominally independent, Innominada was still classified as a dependency of Gothia. Gothian bases in the Far East had already been neglected during tensions leading up to the War of the Sienese Succession, and thus, apart from some incomplete expansions started in 1922-1923, they remained largely in the same state they had been in 30 years prior. No new bases had been built in Innominada's other ports, and the coastal batteries along the coast were severely outdated.

Sylvan discipline at the remaining bases was relatively lax. Apart from its recent operations against Themiclesia in Dzhungestan, Menghe had shown no immediate signs of hostility toward Gothia, which had been a onetime ally of Menghe in the 1900s and early 1910s. Gothian strategists were more concerned about the risk from Dayashina, and thus positioned the Flota Oriental in Puerto Alegre, which was less well-defended than Fort Fernandez but had better logistical facilities. The anti-submarine nets outside the harbor were only partially deployed, to allow better access for civilian shipping, and patrols in San Ramon Bay reflected a peacetime level of wariness.

Menghean preparations

For more than a decade prior, the Menghean Navy had drawn up various plans for the invasion of Innominada, including multiple wargames and tabletop exercises. A common objective of these plans was the early neutralization of the Gothian Navy’s Flota Oriental. Because the Selkiö Naval Treaty limited both Menghe and Gothia to eight capital ships, a direct engagement would be roughly even, but Menghe could increase its advantage by pursuing defeat in detail and decisively engaging the Flota Oriental before it could link up with other Gothian capital ships from Casaterra. In order to reinforce Innominada, the Gothian home fleet would have to cover a distance of some 14,000 kilometers (7,500 nautical miles), which would take about three weeks of continuous cruising at 15 knots. Higher cruise speeds would burn fuel faster, requiring stops in neutral countries along the way, or prior preparations for underway refueling. This would give Menghe a window of opportunity to conduct landings and bombardments along the Innominadan coast.

The initial Menghean battle plan for an attack on Puerto Alegre called for a force of six coastal submarines to infiltrate the harbor under the cover of darkness and sink as many capital ships as possible. A destroyer flotilla would then enter San Ramon Bay, still under the cover of darkness, and ambush any ships attempting to flee to the open ocean. The Menghean battle line, having approached from the east, would patrol the mouth of the bay, as a final measure to prevent any Gothian battleships in the bay from escaping.

An early concern in these plans was the possibility that the Gothian battle fleet would remain in Puerto Alegre, refusing to sortie until reinforcements arrived in Fort Fernandez three weeks later. In exercises, Menghean admirals toyed with the idea of sending the battle fleet into San Ramon Bay to bombard the ships in harbor; this would be more favorable than an open-water engagement, but still risky, as it would draw the Menghean battle line closer to the batteries overlooking the city. A better idea would be to provoke the Gothian fleet into attempting a breakout.

Another concern was that Menghe would have to sustain its fleet 1,600 kilometers (860 nautical miles) from its major fleet base in Quang Pha. Menghean battleships could easily cover this distance with enough fuel to maneuver for a week, but destroyers would have much less endurance to work with, and some older destroyer and torpedo boat models lacked the fuel for a round trip. If the initial operation to destroy the Gothian fleet failed, Menghe would need to sustain a blockade of San Ramon Bay for up to three weeks, all while maintaining enough fuel for chasing and maneuvering if the Gothian ships attempted a breakout, and enough fuel to return home. Menghe had conducted very few experiments with underway refueling, and did not feel confident relying on it in enemy waters over a prolonged period. Looking for alternatives, the Menghean Navy settled on Tanchan Bay, a natural harbor on the east coast of Point Vazquez. Tanchan Bay was only ringed by small fishing towns, but intelligence suggested it was deep enough to serve as a fleet anchorage, albeit an austere one. Even without shore facilities, it would provide a somewhat sheltered place where tankers and supply ships could moor alongside warships to replenish them. And because of the moratorium on new base construction, it was almost entirely undefended. By seizing this natural harbor with a surprise amphibious landing, Menghe would be not only able to sustain its battle fleet just outside the mouth of San Ramon Bay for the weeks necessary to wait out a Gothian breakout, but would also be able to position the Menghean battle fleet as a fleet in being there in the weeks to follow, forcing the Gothian Navy to fight on Menghe's terms.

Admiral Cho's battle plan

The Menghean officer in charge of the operation was Admiral Cho Sŭng-chŏl, who in 1932 had been appointed commander-in-chief of the battle fleet. Cho was one of the Menghean Navy's leading doctrinal theorists, and a primary author of the IMN's early-war doctrine, which emphasized the concentration of the battle fleet against a decisive objective.

In April, spies in Puerto Alegre reported that only two Gothian battleships were stationed in Puerto Alegre, but that both were moored at the north end, well inside the harbor. On this basis, Cho decided on a scaled-back version of the port infiltration plan. After sundown of May 6th, three fleet submarines with midget submarines embarked on their backs would slip into San Ramon Bay and proceed 100 kilometers north, releasing their payloads 30 kilometers from the north end of the bay around midnight. From there, the midget subs would infiltrate the base, and each would attack an assigned target with two torpedoes at around 0400 hours on May 7th.

Shortly after the torpedo attack, and still under the cover of darkness, a Menghean destroyer squadron would head up the middle of San Ramon Bay. This formation would engage any Gothian destroyers, corvettes, or submarine chasers, clearing the way for two groups of four fleet submarines to form a double screen across its entrance. If any Gothian surface ships were caught heading down the bay, the destroyer squadron would skirmish with them and report their location to the submarines, which would move into position to intercept them.

Simultaneously, Menghean marine infantry would come ashore around Tanchan Bay and secure it, then fan out inland to establish a defensive perimeter. Engineers would land next to survey the harbor and begin construction on a pier. The two battleships Songrimsŏng and Gyŏngsan would proceed up the coast to Point Vazquez, where they would bombard the coastal batteries at the mouth of San Ramon Bay. All other capital ships would remain beyond the horizon. If any Gothian ships made it past the gauntlet of submarines and destroyers, the Songrimsŏng and Gyŏngsan would move to head them off, and the rest of the battle fleet would race in at flank speed to join them. Even if both Gothian battleships escaped the torpedo attacks unscathed, this would put them at a 4:1 disadvantage, and they would quickly succumb to concentrated gunfire.

The combined goal of these moves would be to startle the Gothian capital ships into fleeing the safety of Puerto Alegre and running into the trap laid at the mouth of San Ramon Bay. Armed with two 450mm torpedoes each, the midget submarines were unlikely to sink their targets, but they would at least damage them, and send the message that Puerto Alegre's anchorage was not safe and its ships were sitting ducks. Even if this failed, Menghean carrier aircraft from the Meng Ha would begin flying raids over Puerto Alegre at 0700, which would further drive home the message that the Flota Oriental could be sunk in place if it did not move. Cho also hoped that the large landings at Tanchan Bay, seemingly accompanied by only two aging battleships, would provoke the Gothian fleet into attempting a raid on the amphibious force, as would the destroyer activity in San Ramon Bay's southern half. If after these efforts the Gothian battleships still remained seaworthy and in port, Cho was prepared to attempt a second raid on Puerto Alegre the following night, this time with the battleships approaching under the cover of darkness escorted by a destroyer screen. This would free up the Menghean Navy to leapfrog to Fort Fernandez; securing, or at least denying, this base within three weeks would deny it to Gothian reinforcements from Casaterra.