Partition of Bengal :
a) Partition of Bengal in 1905 was the most unpopular of all.
b) The partition led to wide spread protests all across India, starting a new phase of the Indian national movement.
c) The idea of partition was devised to suppress the political activities against the British rule in Bengal by creating a Hindu-Muslim divide.
d) Instead of dividing the Bengali people along the religious line the partition united them.
Anti-partition movement :
a) The boycott of British goods was one such method.
b) The agenda of Swadeshi Movement was still restricted to secure an annulment of partition.
c) The moderates were very much against utilising the campaign to start a full-fledged passive resistance.
d) But the militant nationalists were in favour of extending the movement beyond Bengal and to initiate a full-scale mass struggle.
e) The day Bengal was officially partitioned, 16 October 1905 was declared as a day of mourning.
f) Thousands of people took bath in the Ganga and marched on the streets of Calcutta singing 'Vande Mataram'.
Boycott and Swadeshi Movement in Bengal (1905-1911)
a) Boycott and swadeshi were always interlinked to each other and part of the wider plan to make India self-sufficient.
b) Four major trends can be discerned during the Swadeshi Movement in Bengal.
i) The Moderate Trend
ii) Militant Nationalism
iii) Constructive Swadeshi
iv) Revolutionary terrorism

Causes
a) Annexation policy of British India
In the 1840s and 1850s more territories were annexed through two major policies.
The Doctrine of Paramountcy
a) British claimed themselves as paramount, exercising supreme authority.
b) New territories were annexed on the grounds that the native rulers were corrupt and inept.
The Doctrine of Lapse:
a) If a native ruler did not have a male heir to the throne, the territory was to 'lapse' into British India upon the death of the ruler.
b) Satara, Sambalpur, parts of the Punjab, Jhansi and Nagpur were annexed by the British through this policy.
b) Insensitivity to Indian cultural sentiments 
a) In 1806 the sepoys at Vellore mutinied against the new dress code, which prohibited Indians from wearing religious marks on their foreheads and having whiskers on their chin. They had to replace their turbans with a round hat.
b) It was feared that the dress code was part of their effort to convert soldiers to Christianity.
c) Similarly in 1824, the sepoys at Barrackpur near Calcutta refused to go to Burma by sea since crossing the sea meant the loss of their caste.
d) The sepoys were also upset with discrimination in salary and promotion.
e) Indian sepoys were paid much less than their European counterparts.
f) They felt humiliated and racially abused by their seniors.
c) Immediate cause:
a)The precursor to the revolt was the circulation of rumors about the cartridges of the new Enfield rifle.
b)There was strong suspicion that the new cartridges had been greased with cow and pig fat.
c)The cartridge had to be bitten off before loading (pork is forbidden to the Muslims and the cow is sacred to a large section of Hindus).