Question: What occurred in 2004 that marked the end of the period known as the history of the European Union

Context paragraphs:
Europhile: A Europhile is a person who is fond of, admires, or even loves European culture, society, history, food, etc.  In politics, it may be used to imply Pro-Europeanism, or support for the European Union, often disapprovingly.  In the disapproving case, Europhile stands in contrast to Eurosceptic, which refers to a desire to keep one's country out of the European Union, or a belief that the European Union form of governing will produce worse results than independent European states.

History of the European Union (1993–2004): The history of the European Union between 1993 and 2004 was the period between its creation (replacing the European Economic Community) and the 2004 enlargement.  The European Union was created at the dawn of the post–Cold War era and saw a series of successive treaties laying the ground for the euro, foreign policy and future enlargement.  Three new member states joined the previous twelve in this period and the European Economic Area extended the reach of the EU's markets to three more.

2004 enlargement of the European Union: The 2004 enlargement of the European Union was the largest single expansion of the European Union (EU), in terms of territory, number of states, and population to date; however, it was not the largest in terms of gross domestic product.  It occurred on 1 May 2004.

Dutch passport: Dutch passports are issued to citizens of the Kingdom of the Netherlands (Dutch: "Koninkrijk der Nederlanden" ) for the purpose of international travel.  As the Netherlands only distinguish one category of citizen (Nederlandse (Dutch), NLD), for all countries in the Kingdom, passports are the same for all four countries.  The passport also serves as a means of identification as required by the Dutch law since 1 January 2005 for all persons over the age of fourteen.  Dutch passports are valid for a period of ten years from issuing date.  The passport complies with the rules (EU 2252/04) for European Union passports.  Since 26 August 2006 all passports are issued as a biometric passport with an embedded contactless smartcard RFID chip for storing biometric data.  Every Dutch citizen is also a citizen of the European Union.  The nationality allows for free rights of movement and residence in any of the states of the European Union, other European Economic Area states as well as Switzerland.

European Union wine growing zones: European Union wine growing zones are used in the common European Union wine regulations to regulate certain aspects of winemaking.  The zones differ in terms of climate and examples of what is regulated by wine growing zone are required grape maturity at harvest and allowed levels of chaptalisation.  There are 21 wine producing countries in the European Union, with 14 of them having significant levels of production.  In the 2004-2005 vintage, total European Union wine production was around 184 million hectoliters (4.8 billion gallons) which accounted for nearly 70% of total worldwide production.  Of that total, nearly 55% was classified as table wine with 4% used in the production of grape-based distilled spirits such as Armagnac and Cognac.

Enlargement of the European Union: The process of expanding the European Union (EU) through the accession of new member states began with the Inner Six, who founded the European Economic Community (the EU's predecessor) in 1958, when the Treaty of Rome came into force.  Since then, the EU's membership has grown to twenty-eight, with the latest member state being Croatia, which joined in July 2013.

2007 enlargement of the European Union: The 2007 enlargement of the European Union saw Bulgaria and Romania join the European Union (EU) on 1 January 2007.  Together with the 2004 enlargement of the European Union, it is considered part of the fifth wave of enlargement of the European Union.

Unemployment in Poland: Unemployment in Poland appeared in the 19th century, during the process of industrialization, and was particularly severe during the Great Depression.  During communist rule officially Poland had close to full employment although hidden unemployment existed.  After Poland's transition to a market economy the unemployment rate sharply increased, peaking at above 16% in 1993, then dropped afterwards, but remained well above pre-1993 levels.  Another period of high unemployment occurred in the early 2000s when the rate reached 20%.  As Poland entered European Union (EU) in 2004 and its job market, mass emigration due to unemployment took place lowering the figure.  Since then the rate had fallen until the onset of the 2008 Great Recession.  Recent years have seen an increase in the unemployment rate from below 8% to above 10% (Eurostat) or from below 10% to 13% (GUS).  The rate began dropping again in late 2013.  Polish government (GUS) reported 9.6% registered unemployment in November 2015, while European Union's Eurostat gave 7.2%.  According to Eurostat data, since 2008, unemployment in Poland has been constantly below the EU average.  Significant regional differences in the unemployment rate exist across Poland.

Brussels and the European Union: Brussels in Belgium is considered the "de facto" capital of the European Union, having a long history of hosting the institutions of the European Union within its European Quarter.  The EU has no official capital, and no plans to declare one, but Brussels hosts the official seats of the European Commission, Council of the European Union, and European Council, as well as a seat (officially the second seat but "de facto" the most important one) of the European Parliament.

History of the European Union since 2004: The history of the European Union since 2004 was a period of significant upheaval and reform following the 2004 enlargement of the European Union.  The EU had just taken on ten new members, eight of which were much poorer than the EU average, and took in a further two in 2007 with many more on the way.  It had just created the euro a few years before and had to expand this, and the Schengen Area to its new members.  However this was overshadowed by the late-2000s recession and damaging disputes over the European Constitution and its successor, the Treaty of Lisbon.  Throughout this period, José Manuel Barroso was President of the European Commission and the European People's Party was the largest group in the European Parliament.

Supporting paragraphs: History of the European Union (1993–2004) Enlargement of the European Union
Answer: The process of expanding the European Union