Question: What was the ground force of the Austro-Hungarian Dual Monarchy that Jan Romer joined?
Context: The People's Liberation Army Ground Force (PLAGF) () is the land-based service branch of the People's Liberation Army and it is the largest and oldest branch of the entire Chinese armed forces.  The PLAGF can trace its lineage from 1927; however, it was not officially established until 1948.  As of 2016, the PLAGF has a strength of 1,600,000 personnel making it the largest standing army in the world.  In addition, the People's Liberation Army Ground Force has an estimated 510,000 strong reserve force. The People's Army of Vietnam (PAVN; Vietnamese: "Quân Đội Nhân Dân Việt Nam" ), also known as the Vietnamese People's Army (VPA), is the military force of the Socialist Republic of Vietnam.  The PAVN is a part of Vietnam People's Armed Forces and includes: Ground Force (including Strategic Rear Forces), Navy, Air Force, Border Defence Force, and Coast Guard.  However, Vietnam does not have a specific separate Ground Force or Army branch.  All ground troops, army corps, military districts and specialised arms belong to the Ministry of Defence, directly under command of the Central Military Commission, Minister of Defence, and General Staff of the Vietnam People's Army.  The military flag of the PAVN is the flag of the Socialist Republic of Vietnam, with the words "Quyết thắng (Determination to win)" added in yellow at the top left. The Austro-Hungarian Foreign Service (German: "k. u. k. Auswärtige Dienst" ) was the diplomatic service carrying out the foreign policy of the Emperor of the Austro-Hungarian Empire from the formation of the Dual Monarchy in 1867 until it was dissolved in 1918. The Military of Austria-Hungary, comprising the Armed Forces, War Office, and intelligence organisations of the Dual Monarchy served as one of the Empire's core unifying institutions and primary instruments for defence as well as external power projection.  The history of the Austro-Hungarian military begins when the Habsburgs established hereditary rule over Austrian lands in the 13th century and stretches until the fall of the Habsburgs, at the end of World War I, during which time their armies were among the largest and most significant in Europe.  Though not as powerful as some of its contemporaries, the military of Austria-Hungary's scale, resources, organization, technology and training were one of the central factors determining conferral of 'great power' status on the empire for much of the 19th and early 20th centuries. The Austro-Hungarian economy changed dramatically during the existence of the Dual Monarchy.  The capitalist way of production spread throughout the Empire during its 50-year existence replacing medieval institutions.  Technological change accelerated industrialization and urbanization.  The GNP per capita grew roughly 1.76% per year from 1870–1913.  That level of growth compared very favorably to that of other European nations such as Britain (1%), France (1.06%), and Germany (1.51%).  However, in a comparison with Germany and Britain: the Austro-Hungarian economy as a whole still lagged considerably, as sustained modernization had begun much later.  In 1873, the old capital Buda and Óbuda (Ancient Buda) were officially merged with the third city, Pest, thus creating the new metropolis of Budapest.  The dynamic Pest grew into Hungary's administrative, political, economic, trade and cultural hub. The Austro-Hungarian Army (German: "Landstreitkräfte Österreich-Ungarns" ; Hungarian: "Császári és Királyi Hadsereg" ) was the ground force of the Austro-Hungarian Dual Monarchy from 1867 to 1918.  It was composed of three parts: the joint army ("Gemeinsame Armee ", "Common Army", recruited from all parts of the country), the Imperial Austrian Landwehr (recruited from Cisleithania), and the Royal Hungarian Honved (recruited from Transleithania). Jan Romer (1869 in Lwów – 1934 in Warsaw) was a Polish general and military commander.  Studied in Mödling and joined the Austro-Hungarian Army.  During the First World War fought at the battle of Limanowa (1914) and battle of Gorlice (1914), was wounded twice.  Later he joined the newly recreated Polish Army.  During Polish-Ukrainian War he fought in the liberation of Lwów.  In Polish-Soviet War, commanded the Cavalry Division at the Battle of Koziatyn (April 25-April 27, 1920), one of the most spectacular raids of the Polish cavalry, during the Polish advance towards Kiev.  His troops fought against the Soviet cavalry elite "Konarmia" of Semyon Budyonny.  He commanded the Polish 13th Infantry Division during the Battle of Komarów (August 31, 1920).  Respected by Józef Piłsudski, he was among the first group military personas who confirmed the decoration of Virtuti Militari, highest Polish military decoration, restored after the recreation of the Second Polish Republic, and he himself received the Commander's Cross of that award.  Held position of Inspector of the Army after the war.  Buried in Powązki Cemetery in Warsaw. Austria-Hungary, often referred to as the Austro-Hungarian Empire or the Dual Monarchy in English-language sources, was a constitutional union of the Austrian Empire (the Kingdoms and Lands Represented in the Imperial Council, or "Cisleithania") and the Kingdom of Hungary (Lands of the Crown of Saint Stephen or "Transleithania") that existed from 1867 to 1918, when it collapsed as a result of defeat in World War I.  The union was a result of the Austro-Hungarian Compromise of 1867 and came into existence on 30 March 1867.  Austria-Hungary consisted of two monarchies (Austria and Hungary), and one autonomous region: the Kingdom of Croatia-Slavonia under the Hungarian crown, which negotiated the Croatian–Hungarian Settlement ("Nagodba") in 1868.  It was ruled by the House of Habsburg, and constituted the last phase in the constitutional evolution of the Habsburg Monarchy.  Following the 1867 reforms, the Austrian and the Hungarian states were co-equal.  Foreign affairs and the military came under joint oversight, but all other governmental faculties were divided between respective states. Österreichischer Lloyd (Italian: "Lloyd Austriaco" , English: Austrian Lloyd ) was the largest Austro-Hungarian shipping company.  It was founded in 1833.  It was based at Trieste in the Austrian Littoral, the main port of the Cisleithanian (Austrian) half of the Dual Monarchy. Dual monarchy occurs when two separate kingdoms are ruled by the same monarch, follow the same foreign policy, exist in a customs union with each other and have a combined military but are otherwise self-governing.  The term is typically used to refer to Austria-Hungary, a dual monarchy that existed from 1867 to 1918.
Answer: The Austro-Hungarian Army