The Blitz, from the German word for 'lightning', was the name applied by the British press to the heavy and frequent bombing raids carried out over Britain in 1940 and 1941, during the Second World War.

Adolf Hitler's and Hermann Goering's plans to destroy the Royal Air Force to allow an invasion of Britain were failing, and in response to an RAF raid on Berlin, which itself was prompted by a mistaken German bombing of London, they changed their tactics to the sustained bombing of civilian targets.

This was the beginning of the Blitz - a period of intense bombing of London and other cities that continued until the following May.

Between 7 September 1940 and 21 May 1941, 16 British cities suffered aerial raids with at least 100 long tons of high explosives.

For 57 consecutive days, London was bombed either during the day or night. Fires consumed many portions of the city. Residents sought shelter wherever they could find it - many fleeing to the Underground stations that sheltered as many as 177,000 people during the night. In the worst single incident, 450 were killed when a bomb destroyed a school being used as an air raid shelter.

Londoners and the world were introduced to a new weapon of terror and destruction in the arsenal of twentieth century warfare. The Blitz ended on May 11, 1941 when Hitler called off the raids in order to move his bombers east in preparation for Germany's invasion of Russia.

Getty Images photographer Jim Dyson recently traveled to locations across London to make comparisons between scenes from the Blitz and present-day images, laying one on top of the other.

Then: A blaze in the Negretti and Zambra building at Holborn Circus, London, after a German bombing raid.
Now: A street scene at Holborn Circus on May 1, 2016 in London, England.

Then: A wrecked Humber car on Pall Mall, London after an air raid during the London Blitz, 15th October 1940.
Now: A street scene at Pall Mall in Piccadilly on May 1, 2016 in London, England.

Then: Londoners sheltering on a platform at Bounds Green tube station during an air raid in The Blitz.
Now: A platform at Bounds Green underground station on May 1, 2016 in London, England.

Then: The interior of Westminster Abbey after a German bombing raid.
Now: A view of the choir and altar of Westminster Abbey, on January 13, 2015 in London, England.

Then: A police officer and a soldier inspecting the aftermath of a German air raid, Portman Street, London, 19th September 1940.
Now: A street scene at Portman Sreet near Marble Arch, on April 21, 2016 in London, England.

Then: Bomb damage in London's Leicester Square caused by German air raids during the Blitz, 1941.
Now: A view of the Vue cinema in Leicester Square on May 1, 2016 in London, England.

Then: Soldiers help to clear the debris of Bank Underground Station, in front of The Royal Exchange, London, the morning after receiving a direct hit during the Blitz. The slogan 'Dig For Victory' adorns the Exchange.
Now: A street scene at Bank junction in front of the Royal Exchange on April 25, 2016 in London, England.

Then: A bus is left leaning against the side of a terrace in Harrington Square, Mornington Crescent, in the aftermath of a German bombing raid on London in the first days of the Blitz, 9th September 1940. The bus was empty at the time, but eleven people were killed in the houses.
Now: A view of modern social housing near Mornington Crescent on April 21, 2016 in London, England.

Then: A crater and damaged railings outside Buckingham Palace, London, after the explosion of a German bomb dropped in an air raid the previous day.
Now: Tourists gather outside Buckingham Palace on April 26, 2016 in London, England.

Then: Bomb damage caused by a World War II air raid on Berkeley Square, London, 29th April 1942.
Now: A street scene in Berkeley Square, Mayfair on May 1, 2016 in London, England.

Then: A huge hole in the Strand, where a bomb was dropped during an air raid over central London. It fell near the Gaiety Theatre and the church of St. Mary-le-Strand can be seen in the background. Now: A street scene looking down the Strand towards St.Mary-le-Strand church, on May 1, 2016 in London, England.

Then: A view east down the Thames towards smoke rising from fires in Surrey docks, following the first German air raid of the London Blitz, 7th September 1940. On the right is the Tower of London, and on the right is Tower Bridge.
Now: A view of Tower Bridge on the River Thames on April 25, 2016 in London, England.

Then: An area near St Pancras Station in London showing the damage caused by a German air raid during the London blitz in World War II.
Now: A view of the British Library beside St Pancras hotel on May 3, 2016 in London, England.