SS ''Potrero del Llano'' was an

oil tanker An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk cargo, bulk transport of petroleum, oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quant ...

built in 1912. It sailed for a number of companies, and survived service in the

First World War World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

, only to be torpedoed and sunk by a

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

U-boat U-boats are Submarine#Military, naval submarines operated by Germany, including during the World War I, First and Second World Wars. The term is an Anglicization#Loanwords, anglicized form of the German word , a shortening of (), though the G ...

during the

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

while sailing under the Mexican flag off the coast of

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

. Its sinking contributed to Mexico's decision to enter the war on the side of the Allies. ''Potrero del Llano'' was originally built by

Palmers Shipbuilding and Iron Company Palmers Shipbuilding and Iron Company Limited, often referred to simply as "Palmers", was a United Kingdom of Great Britain and Ireland, British shipbuilder, shipbuilding company. The company was based in Jarrow, County Durham, in north-eastern ...

, Hebburn-on-Tyne as the ''F.A. Tamplin'', for service with T.W. Tamplin & Co., of

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

. It was sold in 1921 to the Belgian company SA d'Armement, d'Industrie & de Commerce, of

Antwerp Antwerp (; ; ) is a City status in Belgium, city and a Municipalities of Belgium, municipality in the Flemish Region of Belgium. It is the capital and largest city of Antwerp Province, and the third-largest city in Belgium by area at , after ...

, and was renamed ''Arminco'', and was sold again in 1930 to the

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...

company Società Italiana Transporti Petroliferi (SITP), of

Genoa Genoa ( ; ; ) is a city in and the capital of the Italian region of Liguria, and the sixth-largest city in Italy. As of 2025, 563,947 people live within the city's administrative limits. While its metropolitan city has 818,651 inhabitan ...

, and was renamed ''Lucifero''. it was interned while docked at

Tampico Tampico is a city and port in the southeastern part of the Mexican state of Tamaulipas. It is located on the north bank of the Pánuco River, about inland from the Gulf of Mexico, and directly north of the state of Veracruz. Tampico is the fif ...

, in Mexico on 10 June 1940 and was seized in 1941 by the

Mexican government The Federal government of Mexico (alternately known as the Government of the Republic or ' or ') is the national government of the United Mexican States, the central government established by its constitution to share sovereignty over the republ ...

and renamed ''Potrero del Llano'' after a town in

Veracruz Veracruz, formally Veracruz de Ignacio de la Llave, officially the Free and Sovereign State of Veracruz de Ignacio de la Llave, is one of the 31 states which, along with Mexico City, comprise the 32 Political divisions of Mexico, Federal Entit ...

. it was operated by Petróleos Mexicanos (

Pemex Pemex (a portmanteau of Petróleos Mexicanos, which translates to ''Mexican Petroleum'' in English; ) is the Mexico, Mexican State ownership, state-owned Petroleum industry, petroleum corporation managed and operated by the government of Mexico, ...

), and was homeported in Tampico. ''Potrero del Llano'' was sailing unescorted from Tampico to

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

in May 1942, carrying 6,132 tons of petroleum. It was sighted by the , under Reinhard Suhren at 07:17 hours on 14 May 1942, while east of the coast of Florida. Suhren noticed an illuminated flag painted on the side of the ship but misidentified it as the

Italian flag The flag of Italy (, ), often referred to as The Tricolour (, ), is a flag featuring three equally sized vertical pales of green, white and red, with the green at the hoist side, as defined by Article 12 of the Constitution of the Italian Repub ...

. Since only ships of the

Mexican Navy The Mexican Navy () is one of the components of the Mexican Armed Forces. The Secretariat of the Navy is in charge of administration of the navy. The commander of the navy is the Secretary of the Navy, who is both a cabinet minister and a career ...

were permitted to display the

Mexican flag The national flag, national flag of Mexico () is a vertical Tricolour (flag), tricolor of green, white, and red with Coat of arms of Mexico, the national coat of arms charge (heraldry), charged in the center of the white stripe. While the meani ...

with the eagle in the centre, the flag shown by the ''Potrero del Llano'' resembled the Italian one, and having decided that the tanker's position and course meant that she could not be Italian, Suhren decided to sink her. ''U-564'' duly torpedoed the ''Potrero del Llano'', which sank with the loss of 13 of its crew. Twenty-two survivors were picked up by and taken to

Miami Miami is a East Coast of the United States, coastal city in the U.S. state of Florida and the county seat of Miami-Dade County, Florida, Miami-Dade County in South Florida. It is the core of the Miami metropolitan area, which, with a populat ...

. One of the survivors, José Reyes Sosa, survived another attack on SS Las Choapas, a tanker sunk by on 27 June 1942, and the fourth Mexican tanker sunk by German submarines. On 20 May 1942 a second tanker, '' Faja de Oro'', was attacked and sunk, this time by . This established a sound ''

casus belli A (; ) is an act or an event that either provokes or is used to justify a war. A ''casus belli'' involves direct offenses or threats against the nation declaring the war, whereas a ' involves offenses or threats against its ally—usually one bou ...

'' for the Mexican government to declare war on the

Axis powers The Axis powers, originally called the Rome–Berlin Axis and also Rome–Berlin–Tokyo Axis, was the military coalition which initiated World War II and fought against the Allies of World War II, Allies. Its principal members were Nazi Ge ...

on 22 May 1942. VIIC uboat line

Notes

References

* {{DEFAULTSORT:Potrero del Llano 1912 ships 1942 in Mexico Maritime incidents in May 1942 Military history of Mexico during World War II Oil tankers Ships of Mexico Ships sunk by German submarines in World War II Tankers of Belgium Tankers of the United Kingdom Ships built on the River Tyne World War I merchant ships of the United Kingdom World War II merchant ships of Italy World War II shipwrecks in the Atlantic Ocean 1942 in Florida Shipwrecks of the Florida coast May 1942 in North America Germany–Mexico relations Germany–United States military relations Mexico–United States military relations Mexican Navy Ship fires