William M. Tweed arrested, ending Tammany grip on New York

Background. Tweed became head of Tammany Hall in 1858 and took control of New York City government after the 1869 election. His power relied on appointees who gave him access to city funds and contractors. However, his reputation was undermined by the Orange Riots of 1870 and 1871, and a mass meeting at Cooper Union in September 1871 appointed a committee to examine the ring's misdeeds.

Decline of Influence. Tweed's rapid decline began in January 1871 when county auditor James Watson died in a sleigh accident. Watson had held the ring's books, and his death led to the release of city accounts to former sheriff James O'Brien. This loss of control over financial records contributed to the political pressure that culminated in Tweed's arrest in October 1871.

Political Consequences. Following his arrest, Tweed was re-elected to the state senate in November 1871 due to personal popularity, but Tammany candidates generally lost. The arrest marked the end of Protestant control of Tammany Hall, which became dependent on Irish Catholic leadership. Tweed was subsequently re-arrested, forced to resign city positions, and replaced as Tammany's leader.