Question: A country's military branch, the equivalent of which in the US contains the Air Defense Artillery, was unprepared for the invasion of the country occupied by the Nazi's. When was the word "Slavs" used in the national anthem of the unprepared country?

Knowledge 1: Slavs
The word "Slavs" was used in the national anthem of the Slovak Republic (1939–1945), Yugoslavia (1943–1992) and the Federal Republic of Yugoslavia (1992–2003), later Serbia and Montenegro (2003–2006). [SEP] Knowledge 2: Josip Broz Tito
In 1968, Tito offered Czechoslovak leader Alexander Dubček to fly to Prague on three hours notice if Dubček needed help in facing down the Soviets. In April 1969, Tito removed generals Ivan Gošnjak and Rade Hamović in the aftermath of the invasion of Czechoslovakia due to the unpreparedness of the Yugoslav army to respond to a similar invasion of Yugoslavia. [SEP] Knowledge 3: United States Army
Currently, the army is divided into the Regular Army, the Army Reserve, and the Army National Guard. The army is also divided into major branches such as Air Defense Artillery, Infantry, Aviation, Signal Corps, Corps of Engineers, and Armor. Before 1903 members of the National Guard were considered state soldiers unless federalized (i.e., activated) by the President. Since the Militia Act of 1903 all National Guard soldiers have held dual status: as National Guardsmen under the authority of the governor of their state or territory and, when activated, as a reserve of the U.S. Army under the authority of the President. [SEP] Knowledge 4: 1939 German ultimatum to Lithuania
The 1939 German ultimatum to Lithuania was an oral ultimatum which Joachim von Ribbentrop, Foreign Minister of Nazi Germany, presented to Juozas Urbšys, Foreign Minister of Lithuania on 20 March 1939. The Germans demanded that Lithuania give up the Klaipėda Region (also known as the Memel Territory) which had been detached from Germany after World War I, or the Wehrmacht would invade Lithuania. The Lithuanians had been expecting the demand after years of rising tension between Lithuania and Germany, increasing pro-Nazi propaganda in the region, and continued German expansion. It was issued just five days after the Nazi occupation of Czechoslovakia. The 1924 Klaipėda Convention had guaranteed the protection of the status quo in the region, but the four signatories to that convention did not offer any material assistance. The United Kingdom and France followed a policy of appeasement, while Italy and Japan openly supported Germany, and Lithuania was forced to accept the ultimatum on 22 March. It proved to be the last territorial acquisition for Germany before World War II, producing a major downturn in Lithuania's economy and escalating pre-war tensions for Europe as a whole.
Knowledge 1: United States Army
Currently, the army is divided into the Regular Army, the Army Reserve, and the Army National Guard. The army is also divided into major branches such as Air Defense Artillery, Infantry, Aviation, Signal Corps, Corps of Engineers, and Armor. Before 1903 members of the National Guard were considered state soldiers unless federalized (i.e., activated) by the President. Since the Militia Act of 1903 all National Guard soldiers have held dual status: as National Guardsmen under the authority of the governor of their state or territory and, when activated, as a reserve of the U.S. Army under the authority of the President. [SEP] Knowledge 2: Josip Broz Tito
In 1968, Tito offered Czechoslovak leader Alexander Dubček to fly to Prague on three hours notice if Dubček needed help in facing down the Soviets. In April 1969, Tito removed generals Ivan Gošnjak and Rade Hamović in the aftermath of the invasion of Czechoslovakia due to the unpreparedness of the Yugoslav army to respond to a similar invasion of Yugoslavia. [SEP] Knowledge 3: Slavs
The word "Slavs" was used in the national anthem of the Slovak Republic (1939–1945), Yugoslavia (1943–1992) and the Federal Republic of Yugoslavia (1992–2003), later Serbia and Montenegro (2003–2006). [SEP] Knowledge 4: Korean War
A major consideration was the possible Soviet reaction in the event that the US intervened. The Truman administration was fretful that a war in Korea was a diversionary assault that would escalate to a general war in Europe once the United States committed in Korea. At the same time, "[t]here was no suggestion from anyone that the United Nations or the United States could back away from [the conflict]". Yugoslavia–a possible Soviet target because of the Tito-Stalin Split—was vital to the defense of Italy and Greece, and the country was first on the list of the National Security Council's post-North Korea invasion list of "chief danger spots". Truman believed if aggression went unchecked a chain reaction would be initiated that would marginalize the United Nations and encourage Communist aggression elsewhere. The UN Security Council approved the use of force to help the South Koreans and the US immediately began using what air and naval forces that were in the area to that end. The Administration still refrained from committing on the ground because some advisers believed the North Koreans could be stopped by air and naval power alone.
Knowledge 1: United States Army
Currently, the army is divided into the Regular Army, the Army Reserve, and the Army National Guard. The army is also divided into major branches such as Air Defense Artillery, Infantry, Aviation, Signal Corps, Corps of Engineers, and Armor. Before 1903 members of the National Guard were considered state soldiers unless federalized (i.e., activated) by the President. Since the Militia Act of 1903 all National Guard soldiers have held dual status: as National Guardsmen under the authority of the governor of their state or territory and, when activated, as a reserve of the U.S. Army under the authority of the President. [SEP] Knowledge 2: Josip Broz Tito
In 1968, Tito offered Czechoslovak leader Alexander Dubček to fly to Prague on three hours notice if Dubček needed help in facing down the Soviets. In April 1969, Tito removed generals Ivan Gošnjak and Rade Hamović in the aftermath of the invasion of Czechoslovakia due to the unpreparedness of the Yugoslav army to respond to a similar invasion of Yugoslavia. [SEP] Knowledge 3: Slavs
The word "Slavs" was used in the national anthem of the Slovak Republic (1939–1945), Yugoslavia (1943–1992) and the Federal Republic of Yugoslavia (1992–2003), later Serbia and Montenegro (2003–2006). [SEP] Knowledge 4: 1939 German ultimatum to Lithuania
The 1939 German ultimatum to Lithuania was an oral ultimatum which Joachim von Ribbentrop, Foreign Minister of Nazi Germany, presented to Juozas Urbšys, Foreign Minister of Lithuania on 20 March 1939. The Germans demanded that Lithuania give up the Klaipėda Region (also known as the Memel Territory) which had been detached from Germany after World War I, or the Wehrmacht would invade Lithuania. The Lithuanians had been expecting the demand after years of rising tension between Lithuania and Germany, increasing pro-Nazi propaganda in the region, and continued German expansion. It was issued just five days after the Nazi occupation of Czechoslovakia. The 1924 Klaipėda Convention had guaranteed the protection of the status quo in the region, but the four signatories to that convention did not offer any material assistance. The United Kingdom and France followed a policy of appeasement, while Italy and Japan openly supported Germany, and Lithuania was forced to accept the ultimatum on 22 March. It proved to be the last territorial acquisition for Germany before World War II, producing a major downturn in Lithuania's economy and escalating pre-war tensions for Europe as a whole.

Answer: 1943–1992