# Britain declares war on Germany (1939)

URL: https://english-history.com/timeline/1939-britain-declares-war-on-germany
Categories: battle, main-event

Britain entered the Second World War after Germany invaded Poland and ignored an ultimatum to withdraw. Within the broader Early 20th Century & World Wars period, mass democracy, the two world wars, Irish partition, economic crisis and the rise of Labour remade the political and social order. This event is placed at 3 September 1939 in the chronology so it can be read alongside the political, military, social and cultural changes around it. The conflict became a struggle for national survival and reshaped Britain's global position.

## Why it matters
The conflict became a struggle for national survival and reshaped Britain's global position.

Ruler at the time: [George VI](https://english-history.com/rulers/george-vi)

## Sources
- [Wikipedia topic lookup — Britain declares war on Germany](https://en.wikipedia.org/wiki/Special:Search?search=Britain+declares+war+on+Germany&go=Go)
- [Encyclopaedia Britannica topic lookup — Britain declares war on Germany](https://www.britannica.com/search?query=Britain+declares+war+on+Germany)
- [Wikipedia — Timeline of British history](https://en.wikipedia.org/wiki/Timeline_of_British_history)
- [The National Archives — twentieth-century resources](https://www.nationalarchives.gov.uk/education/)