Question: When did the country where Apache helicopters are based in the country that recently voted to leave an example of a federal union go to war with Egypt?

full_context: Document 1: Federalism: Until recently, in the absence of prior agreement on a clear and precise definition, the concept was thought to mean (as a shorthand) 'a division of sovereignty between two levels of government'. New research, however, argues that this cannot be correct, as dividing sovereignty - when this concept is properly understood in its core meaning of the final and absolute source of political authority in a political community - is not possible. The descent of the United States into Civil War in the mid-nineteenth century, over disputes about unallocated competences concerning slavery and ultimately the right of secession, showed this. One or other level of government could be sovereign to decide such matters, but not both simultaneously. Therefore, it is now suggested that federalism is more appropriately conceived as 'a division of the powers flowing from sovereignty between two levels of government'. What differentiates the concept from other multi-level political forms is the characteristic of equality of standing between the two levels of government established. This clarified definition opens the way to identifying two distinct federal forms, where before only one was known, based upon whether sovereignty resides in the whole (in one people) or in the parts (in many peoples): the federal state (or federation) and the federal union of states (or federal union), respectively. Leading examples of the federal state include the United States, Germany, Canada, Switzerland, Australia and India. The leading example of the federal union of states is the European Union.
Document 2: British Empire: In July 1956, Nasser unilaterally nationalised the Suez Canal. The response of Anthony Eden, who had succeeded Churchill as Prime Minister, was to collude with France to engineer an Israeli attack on Egypt that would give Britain and France an excuse to intervene militarily and retake the canal. Eden infuriated US President Dwight D. Eisenhower, by his lack of consultation, and Eisenhower refused to back the invasion. Another of Eisenhower's concerns was the possibility of a wider war with the Soviet Union after it threatened to intervene on the Egyptian side. Eisenhower applied financial leverage by threatening to sell US reserves of the British pound and thereby precipitate a collapse of the British currency. Though the invasion force was militarily successful in its objectives, UN intervention and US pressure forced Britain into a humiliating withdrawal of its forces, and Eden resigned.
Document 3: Suez Crisis: The Suez Crisis or the Second Arab -- Israeli War also named the Tripartite Aggression (in the Arab world) and Operation Kadesh or Sinai War (in Israel), was an invasion of Egypt in late 1956 by Israel, followed by the United Kingdom and France. The aims were to regain Western control of the Suez Canal and to remove Egyptian President Gamal Abdel Nasser, who had just nationalized the canal. After the fighting had started, political pressure from the United States, the Soviet Union, and the United Nations led to a withdrawal by the three invaders. The episode humiliated Great Britain and France and strengthened Nasser.
Document 4: Israel: In 1950 Egypt closed the Suez Canal to Israeli shipping and tensions mounted as armed clashes took place along Israel's borders. During the 1950s, Israel was frequently attacked by Palestinian fedayeen, nearly always against civilians, mainly from the Egyptian-occupied Gaza Strip, leading to several Israeli counter-raids. In 1956, Great Britain and France aimed at regaining control of the Suez Canal, which the Egyptians had nationalized (see the Suez Crisis). The continued blockade of the Suez Canal and Straits of Tiran to Israeli shipping, together with the growing amount of Fedayeen attacks against Israel's southern population, and recent Arab grave and threatening statements, prompted Israel to attack Egypt. Israel joined a secret alliance with Great Britain and France and overran the Sinai Peninsula but was pressured to withdraw by the United Nations in return for guarantees of Israeli shipping rights in the Red Sea via the Straits of Tiran and the Canal[citation needed]. The war resulted in significant reduction of Israeli border infiltration.
Document 5: Brexit: In a referendum on 23 June 2016, 51.9% of the participating UK electorate voted to leave the EU, out of a turnout of 72.2%. On 29 March 2017, the UK government invoked Article 50 of the Treaty on the European Union. The UK is thus due to leave the EU on 29 March 2019.
Document 6: Anti-aircraft warfare: Poland's AA defences were no match for the German attack and the situation was similar in other European countries. Significant AA warfare started with the Battle of Britain in the summer of 1940. 3.7-inch HAA were to provide the backbone of the groundbased AA defences, although initially significant numbers of 3-inch 20-cwt were also used. The Army's Anti-aircraft command, which was under command of the Air Defence UK organisation, grew to 12 AA divisions in 3 AA corps. 40-mm Bofors entered service in increasing numbers. In addition the RAF regiment was formed in 1941 with responsibility for airfield air defence, eventually with Bofors 40mm as their main armament. Fixed AA defences, using HAA and LAA, were established by the Army in key overseas places, notably Malta, Suez Canal and Singapore.
Document 7: Federalism: In contrast, Europe has a greater history of unitary states than North America, thus European "federalism" argues for a weaker central government, relative to a unitary state. The modern American usage of the word is much closer to the European sense. As the power of the Federal government has increased, some people have perceived a much more unitary state than they believe the Founding Fathers intended. Most people politically advocating "federalism" in the United States argue in favor of limiting the powers of the federal government, especially the judiciary (see Federalist Society, New Federalism).
Document 8: Anti-aircraft warfare: In Britain and some other armies, the single artillery branch has been responsible for both home and overseas ground-based air defence, although there was divided responsibility with the Royal Navy for air defence of the British Isles in World War I. However, during the Second World War the RAF Regiment was formed to protect airfields everywhere, and this included light air defences. In the later decades of the Cold War this included the United States Air Force's operating bases in UK. However, all ground-based air defence was removed from Royal Air Force (RAF) jurisdiction in 2004. The British Army's Anti-Aircraft Command was disbanded in March 1955, but during the 1960s and 1970s the RAF's Fighter Command operated long-range air -defence missiles to protect key areas in the UK. During World War II the Royal Marines also provided air defence units; formally part of the mobile naval base defence organisation, they were handled as an integral part of the army-commanded ground based air defences.
Document 9: Politics of the United States: The United States is a federal republic in which the president, Congress, and federal courts share powers reserved to the national government according to its Constitution. At the same time, the federal government shares sovereignty with the state governments.
Document 10: Brexit: Brexit (/ ˈbrɛksɪt, ˈbrɛɡzɪt /) is the impending withdrawal of the United Kingdom (UK) from the European Union (EU). In a referendum on 23 June 2016, 51.9% of the participating UK electorate voted to leave the EU; the turnout was 72.2%. On 29 March 2017, the UK government invoked Article 50 of the Treaty on European Union. The European Union (Withdrawal) Act 2018 declares ``exit day ''to be 29 March 2019 at 11 pm UTC.
Document 11: Gamal Abdel Nasser: France and the UK, the largest shareholders in the Suez Canal Company, saw its nationalization as yet another hostile measure aimed at them by the Egyptian government. Nasser was aware that the canal's nationalization would instigate an international crisis and believed the prospect of military intervention by the two countries was 80 per cent likely. He believed, however, that the UK would not be able to intervene militarily for at least two months after the announcement, and dismissed Israeli action as "impossible". In early October, the UN Security Council met on the matter of the canal's nationalization and adopted a resolution recognizing Egypt's right to control the canal as long as it continued to allow passage through it for foreign ships. According to Heikal, after this agreement, "Nasser estimated that the danger of invasion had dropped to 10 per cent". Shortly thereafter, however, the UK, France, and Israel made a secret agreement to take over the Suez Canal, occupy the Suez Canal zone, and topple Nasser.
Document 12: Results of the 2016 United Kingdom European Union membership referendum: United Kingdom European Union membership referendum, 2016 Northern Ireland Choice Votes% Remain a member of the European Union 440,707 55.78% Leave the European Union 349,442 44.22% Valid votes 790,149 99.95% Invalid or blank votes 374 0.05% Total votes 790,523 100.00% Registered voters and turnout 1,260,955 62.69% Source: Electoral Commission
Document 13: Federalism: Federalism in the United States is the evolving relationship between state governments and the federal government of the United States. American government has evolved from a system of dual federalism to one of associative federalism. In "Federalist No. 46," James Madison asserted that the states and national government "are in fact but different agents and trustees of the people, constituted with different powers." Alexander Hamilton, writing in "Federalist No. 28," suggested that both levels of government would exercise authority to the citizens' benefit: "If their [the peoples'] rights are invaded by either, they can make use of the other as the instrument of redress." (1)
Document 14: Army Air Corps (United Kingdom): The Army Air Corps (AAC) is a component of the British Army, first formed in 1942 during the Second World War by grouping the various airborne units of the British Army (which are no longer part of the AAC). Today, there are eight regiments (7 Regular Army and 1 Reserve) of the AAC as well as four Independent Flights and two Independent Squadrons deployed in support of British Army operations across the world. They are located in Britain, Brunei, Canada, and Germany. Some AAC squadrons provide the offensive and air assault elements of 16 Air Assault Brigade through Joint Helicopter Command.
Document 15: Brexit: In a referendum on 23 June 2016, 51.9% of the participating UK electorate voted to leave the EU, out of a turnout of 72.2%. On 29 March 2017, the UK government invoked Article 50 of the Treaty on the European Union. The UK is thus due to leave the EU at midnight on 30 March 2019 Central European Time (11 pm on 29 March 2019 GMT).
ground_truth: 1956
sub_queries: What is an example of a federal union? Answer: the European Union
which country in europe recently voted to leave the European Union Answer: The UK
where are apache helicopters based in the The UK Answer: Britain
when did Britain go to war with egypt Answer: 1956