Was a statement made by the British government in 1917 that would support a Jewish state in Palestine. (in response to the Zionist claims)
Secretary Lord Balfour offered British support, hoping it would persuade wealthy and powerful American Jews to put pressure on the US government to join the war against British enemies.
Promised was confirmed in Balfour Letter of 1919.

Contradicted promised made to the Palestinian Arabs in the McMahon Letter of 1915

William Peel sent by the British govt to investigate the causes of unrest in Palestine.

• 6 months long with 100 witnesses were questioned. July 1937 Lord Peel declared a 400 page report stating that the British Mandate would never succeed and that the only solution was to end it and to partition Palestine into 2 states (Jewish and Arab
  

Reactions
Jews- disliked the plan but it was better than nothing so they accepted it
Arab- rejected as they were unwilling to hand over any land ( which would include the most fertile land with 90 per cent of the orange groves) and over 300,000 Arabs would have to live in a Jewish state

in 1923, The league of Nations gave Britain a Mandate to let Britain have Palestine as the Palestinians 'weren't ready for independence'. On condition that the British had to protect the Palestinian rights and establish a homeland for Jews to get the country ready for independence

To defeat the Ottoman empire during WW1, British wanted support from the Arabs who lived in part of the Ottoman Empire
1915- the British promised to recognise the independence of Arabs in return for their help against Ottoman in the McMahon Letter
However, one year later the British and French drew up a secret agreement which stated that the Arab states would be split up between them. Palestine would go to the British

Reactions
Palestinians- furious as they had not been granted independence immediately like it had been promised in the McMahon letters

After WW1 ended, more than 10000 Jewish immigrants arrived in Palestine. 84,000 by 1922 (11 per cent of the population)
violence broke out as a result between Arab and Jewish communities
1921 all Jewish immigration was banned to calm the situation but immigrants kept coming
violence erupted in Jaffa (main arrival port). 133 Jews and 116 Arabs dead leading to the creation of Irgun to protect Palestinians
Immigration rose again after 1933 following the persecution on Jews in Germany by the Nazis
150,000 Jews in Palestine by 1930 and 25 per cent of the pop in 1936. numbers rose to 450,000 in 1939

Tension rose and turned into violence. Rumor started by 2 rival political parties led to Arabs thinking they were being attacked by Jews. Palestinians angry to the death of 47 Jews and 48 Arabs on May Day 1921.
In August 1929, clashes occur on hold sites in Jerusalem. 4 days of bloody riots and mob violence. 133 Jews and 11 Arabs dead.

General strike organised by the Arabs in 1936 against the British following success of the tactics on other Arab lands.
Striker demanded to end Jewish immigration and to create a national govt of their own as promised in the McMahon Letter
British struggled to maintain control over 6 months until neighboring Arab states intervened