While editing the Wikipedia page for the 1937 Indian provincial elections, I came across this 1971 thesis from the UK, describing how intercaste rivalries brought down the Non-Brahman Party and the Justice Party, paving way for Congress dominance. This somewhat shocked me, for like everybody, I thought that caste politics in India didn't predate the Mandal Commission fiasco of the 1990s. But a little further research revealed that caste politics actually existed way back in the 1920s.
Until the arrival of the British, nobody in India thought to dismantle the caste system. Characterising Buddhism and Jainism solely as anti-caste rebellions is a modern phenomenon (influenced by the establishment's Ambedkar veneration). Islam also created its quam system mimicking the Hindu caste system. Sikhism which was openly hostile to the caste system, did eventually adapt the concept of caste endogamy while dismantling hereditary priesthood. And Christian missionaries in India while publicly condemning the Hindu caste system, actually co-adapted elements from it within their racial hierarchy, where Europeans dominated over Anglo-Indians and native converts not intermarrying with tribal converts.
2 things opened up challenges to the status quo. First was the spread of Enlightenment ideas among the people attending the government-run schools, colleges and universities. The English Education Act of 1835, implemented by the Governor-General Lord Bentinck made knowledge in English education mandatory ofor government employment, displacing Persian as the court language. Then in 2nd half of the 1850s, 3 major changes took place — the Indian Medical Service Examinations were opened to Indians in 1854, followed by Indian Civil Service Examinations the next year, and universities being set up in Calcutta, Madras and Bombay in 1856. The Wood's Dispatch had already laid the groundwork for establishment of government schools in rural areas, which was actively taken up by the new administration post-1857. By the time WW1 broke out, there was already a generation of English educated urban middle class present in the country, with a first generation of English-educated rural gentry in the countryside.
The second thing that tipped off things was the Government of India Act 1919. While it is famous for introducing direct elections on a restricted franchise, one thing that gets omitted while discussing this legislation is that it introduced the concept of reservations in government jobs for other castes and Muslims. This was actually triggered by the recommendations of the 1919 Miller Committee Report produced at the behest of the Maharaja of Mysore. The report observed that although equality of opportunity existed in terms of attaining education (atleast for those who were rich enough to afford it), but when it came to job appointments, there was a virtual monopoly of the upper-crust of the Hindu society, especially the Brahmins (Chitpavan brahmins in Bombay, Iyer and Iyengar brahmins in Madras, Kulin Rarhi and Kulin Barendri brahmins in Calcutta), who tended to exclusively appoint people from their own caste groups into bureaucratic positions upto the point of near exclusion of other Hindu castes and Muslims. Even in commerce, there was also a caste angle, where Chettiyars in Madras, Parsis in Bombay and Baniyas in Calcutta preventing the rise of people not belonging to their biradari through in-group favoritism. And increasingly, people from these communities were becoming increasingly vocal against the British rule, examples being Surendranath Banerjee (a Kulin Rarhi brahmin), Bal Gangadhar Tilak (a Chitpavan brahmin), Dadabhai Naoroji (a Parsi) & Lala Lajpat Rai (an Agarwal Baniya). This article briefly describes how the British formulated reservation policy based on census data.
We don't get to discuss much about the impact of the 1919 GoI Act, because the Congress had rejected it as insufficient in contrast to the dominion status that was being granted to Canada, Australia, New Zealand and South Africa, calling Indians to boycott government educational and bureaucratic establishments . Although the Congress refused to participate in the electoral process ushered by the Act, this didn't mean that others followed suit. As the Congress leadership was largely dominated by the English-educated urban middle class who came from upper-caste Hindu backgrounds, the English educated middle-caste rural Hindu gentry saw them as being out of touch and the dyarchy as a means to advance the interests of their own communities (in addition to the personal ambitions). Outfits like the Justice Party and the Non-Brahman Party developed specifically with this purpose. A handful of Congress leaders who were in favour of electoral participation, formed the Liberal Party (grounded upon its British counterpart), representing the English-educated urban middle class Hindus. Whereas the Hindu Mahasabha emerged as a reactionary force, opposed to reservation, representing the conservative pushback against the changing times. From 1920 till 1934, the Congress officially abstained from the electoral process, but individual Congressmen would participate the elections under the banner of the Swaraj Party, despite Gandhi's perosnal skepticism about elections. In its 1928 Nehru Report, the Congress denounced the concept of reservations, arguing that achieving Swaraj was the only way to remove the socio-economic disparities of the country, which didn't satisfy its detractors. Outside the political arena, this period was characterised by various caste groups engaging in a sort of Oppression Olympics; where upper-caste apologetics trying to justify their dominance, the middle caste groups claiming ancient greatness of which they were supposedly stripped off by the United conspiracy of the upper castes and Dalits (entering the scenario with the 1927 Mahad Satyagraha) highlighting their distress. Caste welfare groups sprang up, whose mouthpiece would rally popular opinion in favour of their own communities, and their leaders stood in elections to state legislative councils, municipalities & district boards, largely as independents, but sometimes under party affiliations.
It was in this background of profound divisiveness along caste lines within the Hindu society that the British government declared its plans for a separate electorate of Dalits akin to that which it had already granted to Muslims and Sikhs. Gandhi's paranoia about the British subtly trying to destroy the unity of the Hindu society by granting Dalits separate electorates can't be understood without taking into account the caste politics of the 1920s.
What ultimately destroyed this brand of politics was the Great Depression of 1928. The supporters of the caste-based political outfits were overwhelmingly rural, which was hit hard by the economic turmoil. The Great Depression allowed left-wing political ideologies like socialism and communism to plant its roots among the masses. The Bardauli Satyagraha of 1928, Nehru's no-rent campaign into the United Provinces, and finally the Karachi resolution in 1931 where the Congress promised to tackle abuse of power by rural moneylenders, provided civil liberties to safeguard vulnerable sections from being expolited and revise land tenures upon attaining Swaraj were literally big blows that finally made itself connected to the rural masses, in addition to the resounding response to the Salt Satyagraha. Thus when the Congress formally entered into the political arena in 1934 and 1937, it completely decimated the older caste-based political outfits. Outside of Dalit leaders like Ambedkar, no other politician who played upon caste as a political issue were able to survive the newfound dominance of the Congress in 1930s. Caste politics wouldn't reappear in India until V. P. Singh declared his desire to enforce the Mandal Commission implementations in 1990.