Serrate was an Allied radar detection and homing device used by night fighters to track Luftwaffe night fighters equipped with the earlier UHF-band "BC" and "C-1" versions of the Lichtenstein radar during World War II.
 It allowed RAF night fighters to attack their German counterparts, disrupting their attempts to attack the RAF's bomber force.
The Battle of the Heligoland Bight was the first "named" air battle of the Second World War, which began the longest air campaign of the war, the Defence of the Reich.
 On 3 September 1939, the United Kingdom declared war on Nazi Germany after the German invasion of Poland, which started the European War.
 The British did not assist Poland by land or sea, but over the ensuing weeks, RAF Bomber Command flew several missions against German targets.
 A number of these air raids were directed at "Kriegsmarine" (German Navy) warships in German ports to prevent their use in the Battle of the Atlantic.
 With the front lines static between September 1939 and May 1940, a period known as the "Phoney War" set in, with little fighting on land or in the air.
 However, at sea, German U-boat (submarine) forces were taking a considerable toll on Allied shipping.
 The Air Ministry decided to launch an attack on German surface ships to prevent them supporting the U-boats in the North Atlantic.
 On 18 December 1939, a force of three RAF bomber squadrons were sent to engage German ships in the Heligoland Bight and sink or damage as many as possible.
 Originally 24 Vickers Wellingtons took off.
 Two turned back owing to engine trouble before reaching German airspace.
 The German reaction was slow.
 Eventually they scrambled strong fighter aircraft forces to intercept.
 Just over 120 aircraft, 80–100 German and 22 British, were involved but only 44 German fighters made contact with the British bombers.
The Yellow Fleet was the name given to a group of fifteen ships trapped in the Suez Canal (in the Great Bitter Lake section) from 1967 to 1975 as a result of the Six-Day War.
 Both sides of the canal had been blocked by ships scuttled by the Egyptians.
 The name "Yellow Fleet" derived from their yellow appearance as they were increasingly covered in a desert sand swept on board.
 After eight years, the only ships that were able to return to their home port under their own power were the German ships "Münsterland" and "Nordwind".
The "Nassau" class were a group of four German dreadnought battleships built for the Imperial Navy.
 They were the German response to the introduction of the "all big gun" British HMS "Dreadnought" .
 The class was composed of "Nassau" , "Rheinland" , "Posen" , and "Westfalen" .
 All four ships were laid down in mid-1907, and completed between May and September 1910.
 Compared to their British contemporaries, the "Nassau"-class ships were lighter and had a wider beam.
 They were two knots slower, because the German ships retained vertical triple-expansion engines as opposed to the high-power turbine engines adopted by the British.
 The ships also carried smaller main guns—11-inch (280 mm) guns rather than the 12-inch (305 mm) guns mounted on the British ships.
The Focke-Wulf Fw 190 "Würger" (English: Shrike ) is a German single-seat, single-engine fighter aircraft designed by Kurt Tank in the late 1930s and widely used during World War II.
 Along with its well-known counterpart, the Messerschmitt Bf 109, the Focke-Wulf 190 Würger became the backbone of the Luftwaffe's "Jagdwaffe" (Fighter Force).
 The twin-row BMW 801 radial engine that powered most operational versions enabled the Fw 190 to lift larger loads than the Bf 109, allowing its use as a day fighter, fighter-bomber, ground-attack aircraft and, to a lesser degree, night fighter.
The Raid on Yarmouth, which took place on 3 November 1914, was an attack by the Imperial German Navy on the British North Sea port and town of Great Yarmouth.
 Little damage was done to the town since shells only landed on the beach, after German ships laying mines offshore were interrupted by British destroyers.
  , a submarine, was sunk by a German mine as it attempted to leave harbour and attack the German ships.
 A German armoured cruiser was sunk after striking two German mines outside its home port.
On 9 February 1945, a force of Allied Bristol Beaufighter aircraft suffered heavy casualties during an unsuccessful attack on the German destroyer "Z33" and its escorting vessels; the operation was labelled "Black Friday" by the surviving Allied aircrew.
 The German ships were sheltering in a strong defensive position in Førde Fjord, Norway, forcing the Allied aircraft to attack through heavy anti-aircraft fire.
 The Beaufighters and their escort of Mustang Mk III fighters from the RAF's No. 65 Squadron were also intercepted by twelve German Focke-Wulf Fw 190 fighters of the "Luftwaffe" fighter wing Jagdgeschwader 5.
 In the resulting attack, the Allies damaged at least two of the German ships for the loss of seven Beaufighters shot down by flak guns.
 Another two Beaufighters and one Mustang were shot down by the Fw 190s.
 Four or five German fighters were shot down by the Allied aircraft, including one flown by German Ace Rudi Linz.
HMS Black Prince was a "Duke of Edinburgh"-class armoured cruiser built for the Royal Navy in the mid-1900s.
 She was stationed in the Mediterranean when the First World War began and participated in the pursuit of the German battlecruiser  and light cruiser  .
 After the German ships reached Ottoman waters, the ship was sent to the Red Sea in mid-August to protect troop convoys arriving from India and to search for German merchant ships.
 After capturing two ships, "Black Prince" was transferred to the Grand Fleet in December 1914 and was sunk during the Battle of Jutland in May 1916, with the loss of all hands.
The "Duke of Edinburgh"-class cruiser was a class of two armoured cruisers built for the Royal Navy in the first decade of the 20th century.
 They were the first British armoured cruisers designed to work with the battlefleet rather than protect merchant shipping.
 After commissioning, they were assigned to the Atlantic, Channel and Home Fleets until 1913 when they were transferred to the Mediterranean Fleet.
 After the start of World War I in August 1914, the sister ships participated in the pursuit of the German battlecruiser  and light cruiser  .
 After the German ships reached their refuge in Ottoman Turkey, the ships were ordered to the Red Sea for convoy escort duties.
 They captured three German merchant ships before they returned to home at the end of the year.
The Khan al-Assal chemical attack was a chemical attack in Khan al-Assal, Aleppo, Syria, on 19 March 2013, which according to the Syrian Observatory for Human Rights resulted in at least 26 fatalities including 16 government soldiers and 10 civilians, and more than 86 injuries.
 Immediately after the incident the Syrian government and opposition accused each other of carrying out the attack, but neither side presented clear documentation.
 The Syrian government asked the United Nations to investigate the incident, but disputes over the scope of that investigation led to lengthy delays.
 In the interim, the Syrian government invited Russia to send specialists to investigate the incident.
 Samples taken at the site led them to conclude that the attack involved the use of sarin, which matched the assessment made by the United States.
 Russia held the opposition responsible for the attack, while the US held the government responsible.
 UN investigators finally arrived on the ground in Syria in August (with a mandate excluding the evaluation of culpability for the chemical weapons attacks), but their arrival coincided with the much larger-scale 2013 Ghouta attacks which took place on 21 August, pushing the Khan al-Assal investigation "onto the backburner" according to a UN spokesman.
 The UN report, which was completed on 12 December, found "likely use of chemical weapons in Khan al-Assal" and assessed that organophosphate poisoning was the cause of the "mass intoxication".

Question: What unsuccessful 1945 attack involved German ships. the RAF, and Focke-Wulf fighters?
Answer: Black Friday