Information:  - ód Army was one of the Polish armies that took part in the Invasion of Poland of 1939. It was officially created on 23 March 1939 with the task of filling the gap between Pozna Army in the north and Kraków Army in the south. Commanded by Juliusz Rómmel, it consisted of five infantry divisions and two cavalry brigades with support from the air force.  - Kraków Army was one of the Polish armies which took part in the Polish Defensive War of 1939. It was officially created on March 23, 1939 as the main pivot of Polish defence. It was commanded by Gen. Antoni Szylling. Originally, Kraków Army was to be made of seven infantry divisions, two cavalry brigades and one mountain brigade. On September 1, 1939, General Szyllling had the force which consisted of five infantry divisions, two cavalry brigades and one brigade of mountain infantry. Altogether, the army was made of 59 battalions, 29 squadrons, 352 cannons, 90 tanks, two armoured trains and 44 planes. These forces were not enough to halt German advance, especially in the area north of Czstochowa, where Kraków Army connected with ód Army. Main thrust of Wehrmacht panzer units was directed there, and this area was defended only by the Polish 7th I.D., which was destroyed in the early days of September 1939, opening the way towards central Poland.  - The French Military Mission to Poland was an effort by France to aid the nascent Second Polish Republic after it achieved its independence in November, 1918, at the end of the First World War. The aim was to provide aid during the Polish-Soviet War (19191921), and to create a strong Polish military to serve as a useful ally against Germany. It was an advisory body consisting of about 400 French officers attached to staffs of Polish units at various levels. Although the French mission was small numerically, its effect was substantial in improving the organisation and logistics of the Polish army. It worked in parallel with the smaller British Military Mission to Poland. It existed from 1918 to 1939.  - Operational Group (abbreviated GO) was the highest level of tactical division of the Polish Army before and during World War II and the Invasion of Poland. It was corps-sized, although various Operational Groups varied in size. Operational groups first appeared in Polish tactical scheme during the Polish-Bolshevik War, most probably under the influence of French Military Mission to Poland. After the war they were dissolved.  - World War II (often abbreviated to WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945, although related conflicts began earlier. It involved the vast majority of the world's nationsincluding all of the great powerseventually forming two opposing military alliances: the Allies and the Axis. It was the most widespread war in history, and directly involved more than 100 million people from over 30 countries. In a state of "total war", the major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, erasing the distinction between civilian and military resources. Marked by mass deaths of civilians, including the Holocaust (in which approximately 11 million people were killed) and the strategic bombing of industrial and population centres (in which approximately one million were killed, and which included the atomic bombings of Hiroshima and Nagasaki), it resulted in an estimated 50 million to 85 million fatalities. These made World War II the deadliest conflict in human history.  - The 55th Infantry Division ( Polish : 55 . Dywizja Piechoty ) was a reserve unit of the Polish Army during the interbellum period , which took part in the Polish September Campaign . Commanded by Colonel Stanislaw Kalabinski , it was part of Operational Group Silesia of the Kraków Army .  - Antoni Szylling (31 August 1884 - 17 June 1971) was a Polish general, considered, along with Generals Wiktor Thommée and Stanisaw Maczek, to have been one of the most successful Polish Army commanders during the Invasion of Poland of 1939.    Given the information above, choose from the list below the object entity that exhibits the relation 'conflict' with the subject '55th infantry division '.  Choices: - invasion of poland  - world war  - world war ii
The answer to this question is:
world war ii