For the 110th anniversary of the Bulgarian Merchant Shipping the Bulgarian Post issued four stamps, which shows us merchant ships issued under Bulgarian flag. The 12 Lev shows the KNYAGUINYA MARIA LOUISA.

Thanks to Mr. Andreas von Mach I got the correct name of the first liner of Bulgaria, he got his information from a small booklet with all Bulgarian merchant and war ships.He gives that she is the KNYAGUINYA MARIA LOUISA; information given by the stamp is that her name was MARIE-LUISE; but I could not find any Bulgarian ship under that name. I have seen also the name KNYAGUINYA MARIA LUISA (Dictionary of Disasters at Sea) and KNYAGUINYA MARIA LOUISE (The Worlds Merchant Fleets 1939 by Roger Jordan).
Lloyds Register spells her name as KNYAGUINYA MARIA LOUISE.

Built under yard No. 115 by Société Anonyme des Chantiers et Ateliers de Provence S.A., Port de Bouc, France, for Cie Marseillaise de Nav. A Vapeur (Fraissinet & Cie. Managers), Marseille, France.
1919 Launched under the name FELIX FRAISSINET
Tonnage 3.821 gross, 2,237 net. Dim. 111.5 x 14.2 x 6.9m. , length bpp 1007.4m..
One triple expansion steam engine 502 nhp., speed 11.5 knots.
Passenger accommodation for 33 passengers.
December 1919 completed, Homeport Marseille.
.
1933 Sold to Société Commerciale Bulgare de Navigation à Vapeur (BMSC) at Varna..
Renamed KNYAGUINYA MARIA LOUISA, named after Princess Maria Louisa.of Bulgaria (1933-
Accommodation for 28 passengers.
The company did have services from Varna-Bourgas to Antwerp and Hamburg. Varna to Italy. Varna to Piraeus-Alexandra-Port Said and other Mediterranean ports.

30 May 1941 during a bombing raid by British aircraft at the port of Piraeus, the KNYAGUINYA MARIA LOUISA underway from Varna to Piraeus, was hit in the entrance of the port, her deck cargo of benzine in drums caught fire and this detonated her cargo of munitions. The ship blew up with and explosion that sank three other ships in the harbour, and caused some 200 causalities.
There was heavy damage to port installations.

Source; Mr. Von Mach. Die Schiffe der Bulgarischen Marinen 1878-1945. And the two all mentioned books. John D Stevenson.

Additional info received from Mr.Fonseca with thanks.
THE S/V PRINCESS MARIA LUISA
In the early 30s of the past century, BMSC opened a new line to the Western Mediterranean. For the purpose of servicing it, the steamer PRINCESS MARIA LUISA was purchased. She had been owned by Fraissinet, a French company, and had been flying the French flag under the name of FELIX FRAISSINET since 1919.

On 18 December 1933, the Bulgarian flag was hoisted on the new vessel of BMSC in Marseilles. She was named after the daughter of the Bulgarian royal family, Maria Luisa. The vessel was purchased after she had been overhauled and her price was 1,100,000 francs (6,000,000 Bulgarian levs). She was of the cargo-and-passenger type. Her deadweight tonnage was 5075 t., her length – 111.5 m, and her beam – 14.5, and her main engine was a 1,400 hp steam engine. She had 6 holds with a pair of derricks each. A single derrick was capable of lifting up to 20 tons of cargo, which made her valuable for the cargo handling operations in the Mediterranean, where a large number of ports were call made. She also had the capability of transporting livestock, Bulgaria’s main export of the time, on her deck. Further, she had first-class cabins for 26 passengers, second-class – for 14 passengers, and third-class – for 30 passengers.
As soon as she was purchased, she started to play a major part in Bulgaria’s sea trade. Her first voyage, under the command of Captain Dimitar Furnajiev, was from Marseilles to Port Said in Egypt. Once there, she was laden with 4,000 tons of salt and 400 tons of different cargo for Istanbul and Bulgaria.

In the following years, alongside with the Balkan, she contributed to the lowering of the freightage for transporting eggs from Bulgaria to Spain. The foreign shipping agencies had raised the freightage from 5 to 8 shillings per crate of eggs from a Bulgarian port to Barcelona. Owing to the PRINCESS MARIA LUISA, the haulage price was reduced to 4 shillings.

In 1934, the PRINCESS MARIA LUISA and the Balkan started servicing the Continental line. Initially it reached Antwerp, Belgium, and Rotterdam, the Netherlands, and later also England, Germany, Denmark, and Norway. Thus, the PRINCESS MARIA LUISA was among the first Bulgarian ship to fly the national flag in the Atlantic.
In the month of September of the same year, the steamer’s crew, also supported by her Captain, Vasil Popov, went on strike. Their demands for a quarter of their payment to be in foreign currency were fulfilled.
In the early days of World War II, the PRINCESS MARIA LUISA continued to transport goods to Naples, Italy, and Marseilles, France.

On 29 April 1941, the ships of BMSC were militarized. The PRINCESS MARIA LUISA was chartered to the German command on the Balkans. In May 1941, PRINCESS MARIA LUISA and BURGAS were in the port of Thessalonica. The Commandant of the BURGAS, Petar Abajiev, refused to carry out the German request to carry aviation bombs and petrol to Piraeus. The Captain of the PRINCESS MARIA LUISA, Ivan Tomov, deferred to the Administration of BMSC and accepted the dangerous cargo.
On 27 may 1941 they berthed in Piraeus. The unloading started on 30 May. Then, a fire started in one of the holds. The firefighting party failed to extinguish it. The fire was drawing nearer to the aviation bombs.
Captain Tomov dismissed the crew and remained onboard with a few other people. A German tug started towing the vessel. Soon after the ship got underway, the bombs exploded. The hull was torn apart and the PRINCESS MARIA LUISA sank in the port. Some buildings and storehouses in the vicinity were also heavily damaged. Captain Ivan Tomov, First Mate Georgi Babev (the son of Captain Nikola Babev, killed in 1929 when the VARNA went down), First Engineer Petar Charakchiev, Motormen Georgi Vinarov and Georgi Georgiev, Radioman Stoimen Zakhariev, and Assistant Cook Todor Stoilov, perished.

The PRINCESS MARIA LUISA is the first casualty of the fleet of BCSA. With their act of heroism, the Bulgarian sailors saved the port and a part of Piraeus from a disaster.
In the 1990s, the Municipality of Piraeus was requested to allow the setting up of a commemorative plate with the names of the Bulgarian sailors. Unfortunately, it was not taken into consideration.

Source: Naval Museum Varna.
https://www.wrecksite.eu/wreck.aspx?136319
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