Czechoslovakism is a term for the political and cultural conception of a unified Czechoslovak nation and disapproval of differentiating separate nations of Czechs and Slovaks

Slovaks

The Slovaks, Slovak people, or Slovakians are a West Slavic people that primarily inhabit Slovakia and speak the Slovak language, which is closely related to the Czech language.Most Slovaks today live within the borders of the independent Slovakia...

. This nation was made ideologically for a newborn country, which needed to identify itself on national level. This national ideology was made for a relatively new country: Czechoslovakia was established in 1918, but the nations living there had been part of Habsburg

Habsburg

The House of Habsburg , also found as Hapsburg, and also known as House of Austria is one of the most important royal houses of Europe and is best known for being an origin of all of the formally elected Holy Roman Emperors between 1438 and 1740, as well as rulers of the Austrian Empire and...

 Monarchy

Monarchy

A monarchy is a form of government in which the office of head of state is usually held until death or abdication and is often hereditary and includes a royal house. In some cases, the monarch is elected...

 since 1526, followed by the Austro-Hungarian Empire.

While the Cleveland Agreement in 1915 and the Pittsburgh Agreement

Pittsburgh Agreement

The Pittsburgh Agreement paved the way for the creation of the state of Czechoslovakia and was signed by a group of 20 Czechs, Slovaks, and Rusyns on May 31, 1918...

 on May 31, 1918 made allowance for a Czech nation and a Slovak nation, the Washington Czechoslovak declaration of independence

Czechoslovak declaration of independence

The Czechoslovak Declaration of Independence was drafted by Thomas Masaryk and published by the nation's Paris based Provisional Government on October 18, 1918...

 on October 18, 1918 mentions only the one Czechoslovak nation. The published version of the Slovak Martin Declaration (October 30, 1918) mentioned "the Slovak branch of the unified Czecho-slovak nation". The original approved text of the Martin Declaration and proceedings were "lost" after the return of Milan Hodža

Milan Hodža

Milan Hodža was a prominent Slovak politician and journalist, serving from 1935 to 1938 as the Prime Minister of Czechoslovakia and in December 1935 as the acting President of Czechoslovakia...

 from Budapest. The published text was claimed to be a forgery. Hodža didn't succeed with his proposed changes but had the text willfully changed in the following night. The change consisted in removing the Slovak demand of national self-determination.

This ideology was essential for the creation of Czechoslovakia in 1918, and for the establishment of the Czechoslovak Constitution of 1920

Czechoslovak Constitution of 1920

After World War I, Czechoslovakia established itself and as a republic and democracy with the establishment of the Constitution of 1920. The constitution was adopted by the National Assembly on 29 February 1920 and replaced the provisional constitution adopted on 13 November 1918.The introduction...

. Statistics from the era of the First Republic (1918–1938)

Czechoslovak Republic (1918–1938)

The First Czechoslovak Republic , refers to the first Czechoslovak state that existed from 1918 to 1938. The state was commonly called Czechoslovakia . It was composed of Bohemia, Moravia, Czech Silesia, Slovakia and Subcarpathian Ruthenia...

 mentioned Czechoslovaks rather than Czechs or Slovaks:

---- Nationalities of Czechoslovakia 1921 ----
total population	| 13,607.385
Czechoslovaks	8,759.701	64.37 %
Germans Germany Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...	3,123.305	22.95 %
Hungarians	744.621	5.47 %
Ruthenians Ruthenians The name Ruthenian |Rus']]) is a culturally loaded term and has different meanings according to the context in which it is used. Initially, it was the ethnonym used for the East Slavic peoples who lived in Rus'. Later it was used predominantly for Ukrainians...	461.449	3.39 %
Jews Jews The Jews , also known as the Jewish people, are a nation and ethnoreligious group originating in the Israelites or Hebrews of the Ancient Near East. The Jewish ethnicity, nationality, and religion are strongly interrelated, as Judaism is the traditional faith of the Jewish nation...	180.534	1.33 %
Poles Poles thumb|right|180px|The state flag of [[Poland]] as used by Polish government and diplomatic authoritiesThe Polish people, or Poles , are a nation indigenous to Poland. They are united by the Polish language, which belongs to the historical Lechitic subgroup of West Slavic languages of Central Europe...	75.852	0.56 %
Others	23.139	0.17 %
Foreigners	238.784	1.75 %

Not all people agreed with the ideology (mainly Slovaks). During World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, when Czechoslovakia was occupied by the German Third Reich, the Slovak Republic was created as a client state

Client state

Client state is one of several terms used to describe the economic, political and/or military subordination of one state to a more powerful state in international affairs...

 of Nazi Germany, and Subcarpathian Ruthenia was annexed by Hungary

Hungary

Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...

. After World War II, Czechoslovakia was reunited, but the ideology of one nation was not fully restored.

After the 1960 Constitution of Czechoslovakia

1960 Constitution of Czechoslovakia

The Constitution of the Czechoslovak Socialist Republic , promulgated on 11 July 1960 as the constitutional law 100/1960 Sb., codified the Communist regime in Czechoslovakia...

 had limited the autonomy granted to Slovakia, the Constitutional Law of Federation

Constitutional Law of Federation

The Constitutional Law of Federation was a constitutional law in Czechoslovakia adopted on 27 October 1968 and in force from 1969 – 1992, by which the unitary Czechoslovak state was turned into a federation.-Federation:...

 of 1968 stated that Czechoslovakia was a federation of two national republics and introduced dual citizenship.