|Dornier Do.17z in formation|
5K + AR (Werke no. 1160) had been part of the 7th squadron of the 3 bomber wing or 7/KG3 based in Antwerp-Deurne in occupied Belgium. The crew of four were Unteroffizier Reinhard and Ritzel who were listed as Missing, Gefrieter Huhn who was killed and only Feldwebel Essmert was captured. However Historian Chris Goss stated that two crew men were killed (one buried in Holland and One at the German Cemetery in Staffordshire) with two being captured. 
The BBC website (http://m.bbc.co.uk/news/uk-22380915?ocid=socialflow_twitter_bbcnews ) has a recreation of the crash. During a raid on the South east of England (Some of 7 Staffel were chalked to attackk the RAF base at West Malling ) others seem to have been raiding the coastal areas such as Margate, Folkestone and Dover around lunch time returning to base at around 12:50.  Whatever her target 5K + AR was damaged by fire from an RAF Boulton-Paul Defiant most likely from 264 Squadron which claimed several Do. 17s on 26th August. Fw. Essmert would have brought his bomber down to a low altitude to draw less attention and to use the aircraft's superior low altitude handling to his advantage. Also it meant if he lost power it would be easier to bring in for a crash landing. It was a lost cause though, losing power he was forced to attempt a ditched landing over the Goodwins. The sea isn't an ideal surface to land on and it appears a wing was clipped and it flipped the aircraft which is why she is laying on her back.
So why is this find so important?
The Luftwaffe had three main bombers during the battle of Britain, the ubiquitous Heinkel He 111, the Junkers Ju 88 and the Dornier Do. 17z. Where as the Heinkel and Junkers would continue on as mainstays of the Luftwaffe's Kampflieger the Dornier was gradually retired by late 1941 and replaced by the Dornier Do. 215 and Do. 217 which used similar airframes but were different aircraft altogether. No Do. 17s are known to have survived and the last was scrapped in Finland in the 50s. Most of the Luftwaffe ones were either sold on, scrapped for their raw materials or converted for other uses.
It was one of the first modern bombers to be added to the fledgling Luftwaffe's stables in the mid thirties and was tested extensively in Spain by the Condor Legion. Although she was graceful, very manoeuvrable and her slim lines made her a hard target to hit compared to the bulky Heinkel, her bomb load was lacking as was the range. As the war went on and Luftwaffe strategists had to look at the very real possibility of prolonged fighting on the front with the need to strike further behind static lines rather than impressive high speed low altitude raids. The Ju 88 and He 111 were considered better suited and the Dornier line discontinued.
Parts and bits are held by various museums and collectors but not a complete airframe (minus cockpit glazing and undercarriage doors). Although she is made of Aluminium which degrades very quickly in salt water, it has been buried under the shifting sands which should hopefully have protected it.
As the planned lift occurs this weekend archaeologists and historians hold their breath to see what they will discover in her fuselage.
 Aircraft casualties in Kent Part 1; 1939 to 1940, Kent aviation historical research society, Meresborough books, Rainham, 1990 p.39
 Aircraft casualties in Kent Part 1, p. 39 entry numbers: 554, 561 and 567 all Dornier Do.17z's of 7/ Kg 3
Jon Lake, The battle of Britain, Amber books, London, 2000