was one of eight Itasy
class frigates commissioned by the Royal Merina Navy during the Second World War.
The invasion of Poland was of little concern to the Kingdom of Imerina, which remained neutral after the outbreak of war. Much of the fighting was limited to eastern Europe. The Treaty of Tolagnaro, which had dragged Imerina into the First World War, was not applicable. German surface raiders were a potential threat, but the war at sea had not escalated to the point where neutrality was meaningless. On the 25th of October 1939, a Merina merchant ship was halted by the Graf Spee
and subsequently released.
The situation began to deteriorate rapidly in 1940. Losses in the Atlantic Ocean increased dramatically following the fall of France. Merina ships were targeted for the first time, regardless of whether they travelled alone or in a British convoy. To make matters worse, Italy had joined the war. There were fears that German and Italian submarines would soon operate from bases in Italian East Africa, bringing the submarine war much closer to home. In response to the apparent threat, the Royal Merina Navy (RMN) requested emergency funds for an anti-submarine programme. Parliament approved the request October with little hesitance. Many members of the nobility had a vested interest in protecting exports to Britain and elsewhere.
Twelve civilian trawlers were immediately requisitioned and converted into anti-submarine vessels. This was an interim measure and the conversions were haphazard. Four gunboats of the Alaotra class were similarly converted, though they had been built with the addition of anti-submarine equipment in mind. These vessels patrolled Merina waters and escorted merchant ships along the eastern coast of Africa, allowing the Royal Navy and the South African Seaward Defence Force to concentrate their efforts elsewhere.
Imerina formally entered the Second World War occurred in May 1942 when the nation invaded and occupied Vichy-controlled French Imerina. While the threat from Italian East Africa had evaporated, long-range German and Japanese submarines were an emerging danger. A class of eight new anti-submarine warfare vessels was ordered that same month. These were to be purpose-built ships, significantly more capable than the conversions that came before. Equipment would be sourced internationally as required. Each member of the class was named after a lake, with the lead ship designated Itasy
was laid down as the fourth member of the class in June 1942 after a slip in Mahajanga became available. The ship was launched six months later and entered service in November 1943.
Of the anti-submarine ships commissioned by the Royal Merina Navy during the Second World War, the Itasy
class were among the best armed. The main battery consisted of four 102 mm (4-inch) guns distributed between two mounts, one forward and one aft. These were true dual-purpose guns, unlike the old 120 mm (4.7-inch) weapons fitted to the Alaotra
class and Merina destroyers. A director immediately behind the bridge provided centralised fire control. Illumination rockets could be launched from the forward turret during a night engagement. The secondary battery changed dramatically as the war progressed, but Tsimanampetsotsa
initially carried four twin 13.2 mm (0.52-inch) Hotchkiss machine guns and a pair of 40 mm (1.6-inch) Bofors guns in a single twin mount. The Hotchkiss machine guns were obsolete, but they were manufactured under licence in Imerina and available at the time. The Bofors guns were manufactured in the United States and provided under lend-lease.
class were the first Merina ships to carry the Hedgehog anti-submarine mortar, with a single launcher fitted just forward of the bridge. This system supplemented the depth charge racks and K guns mounted near the stern. A quadruple 533 mm (21-inch) torpedo launcher was also carried. While submarines were the principle threat, merchant raiders such as the various Italian ships named Ramb
were also a concern. The torpedoes would shorten any engagement with such a large ship, and also allow the Itasy
class to partially replace RMN destroyers when they were unavailable. Later Merina frigates, optimised for cost rather than capability, did not carry any torpedoes. The main battery on these later ships was also reduced.
Displacing 1400 long tons (1422 t), the Itasy
class was similar in size to the Royal Navy's Loch class. Two screws driven were fitted, with a pair of three-drum boilers providing power. Tsimanampetsotsa
had a design speed of 21 knots (39 km/h, 24 mph), but could slightly exceed this speed in good conditions if her engines were pushed to the limit. The crew varied over time, but normally included between 115 and 135 persons. Larger crews were required as the anti-aircraft armament increased towards the end of the war. Sensors were acquired from the United Kingdom at first and initially included an HF/DF antenna, the Type 271 surface search radar, and the Type 144 sonar array.
After her commissioning in November 1943, Tsimanampetsotsa
was assigned to convoys running between Imerina and India. The ship also escorted British convoys to and from Aden and the Seychelles on occasion. In March 1944 the 13.2 mm Hotchkiss machine guns were removed and replaced with an identical number of 20 mm Oerlikon cannons. In September the German submarine U-861
was successfully engaged with the ship's Hedgehog mortar. This was the only confirmed submarine kill achieved by Tsimanampetsotsa
during the war. By December the submarine threat had diminished and the RMN started planning for offensive operations against Japan. Two of the existing 20 mm Oerlikon mounts were relocated to the quarterdeck. In their place, two single 40 mm Bofors guns were fitted. The Type 271 surface-search radar was replaced with the new Type 277 and the main gun director was modified to include fire control radar. In January 1945 Tsimanampetsotsa
and three of her sisters were deployed to the coast of Burma. There they supplemented the existing escort of the battlecruiser Radama I
. Though thoroughly obsolete, the old battlecruiser had been called upon to support British landing operations in the region. Tsimanampetsotsa
's role in the war had reached its end by June. Radama I
was withdrawn to Ceylon for the rest of the war.
All ships of the Itasy
class were to be retained after the war, though half would be converted into patrol ships. Tsimanampetsotsa
was among those selected for conversion. Her torpedo tubes were removed in 1947, along with the two single Bofors gun mounts fitted during the war. In the early 1960s, the ship intercepted a number of illegal arms shipments bound of the socialist FSN, which was then in open revolt. Tsimanampetsotsa
was retained after General Ratsilikaina overthrew the Merina government in 1963, though maintenance was continuously deferred from this point onward. She was deemed unfit for service in 1970 and scrapped the following year.