The statement that the banning of Sati is attributed to the annihilation of a major social evil in colonial India is largely accurate, but a nuanced understanding reveals complexities beyond a simple narrative of colonial benevolence. Sati, the practice where a widow immolated herself on her husband's funeral pyre, was indeed a deeply entrenched and horrific social evil, particularly prevalent among certain upper castes in parts of India.

From a humanitarian perspective, the abolition of Sati by Lord William Bentinck in 1829, largely due to the persistent efforts of Indian reformers like Raja Ram Mohan Roy, was a significant step towards social reform. It saved countless women from a gruesome and often coerced death, challenging a practice that was justified by religious dogma but inflicted immense suffering. The British colonial administration, initially hesitant due to concerns about interfering with religious customs and potentially inciting rebellion, eventually acted under pressure from both internal reformers and evangelical groups in Britain.

However, attributing the ban solely to the 'annihilation of a social evil' by the colonial state overlooks several critical dimensions:

1. Indian Agency: The movement against Sati was spearheaded by enlightened Indian reformers like Raja Ram Mohan Roy, who meticulously argued against the practice using Hindu scriptures themselves, demonstrating that it was not a universally sanctioned religious duty but a perversion. Their intellectual and social activism provided the moral and intellectual groundwork for the ban.

2. Colonial Self-Interest and Legitimacy: While the ban had humanitarian outcomes, it also served the colonial state's agenda. By portraying themselves as modernizers and civilizers, the British could legitimize their rule over India, contrasting their 'enlightened' governance with what they depicted as 'barbaric' native customs. This narrative helped to justify their 'civilizing mission' and reinforce their moral authority.

3. Selective Intervention: The British often intervened selectively in Indian social practices. While Sati was banned, other practices like child marriage or the caste system, which were also deeply problematic, were either tolerated or addressed much later and less forcefully. This selectivity suggests that interventions were often guided by political expediency and the desire to maintain social order rather than a consistent commitment to universal human rights.

4. Impact on Women's Status: While the ban saved lives, it did not fundamentally alter the subordinate status of widows or women in general within Indian society. Widows continued to face social ostracism, economic deprivation, and limited rights. The ban was a necessary but not sufficient condition for broader gender equality.

In conclusion, the banning of Sati was undeniably a crucial step in eradicating a major social evil. However, it was a complex event shaped by the confluence of Indian reformist zeal, colonial administrative power, and the broader political economy of British rule. While it brought an end to a horrific practice, it also became a tool for colonial self-legitimization, highlighting the intricate relationship between social reform and power dynamics in colonial India.