spent the rest of the war there and was discharged less than a month after Armistice Day, following a promotion to first lieutenant. Warren remained in the United States Army Reserve until 1934, rising to the rank of captain. City and district attorney In late 1918, Warren returned to Oakland, where he accepted a position as the legislative assistant to Leon E. Gray, a newly-elected member of the California State Assembly. Shortly after arriving in the state capital of Sacramento, Warren was appointed as the clerk of the Assembly Judiciary Committee. After a brief stint as a deputy city attorney for Oakland, in 1920 Warren was hired as a deputy district attorney for Alameda County. By the end of 1924, Warren had become the most senior person in the department outside of the district attorney, Ezra Decoto. Though many of his professional colleagues supported Calvin Coolidge, Warren cast his vote for Progressive Party candidate Robert La Follette in the 1924 presidential election. That same year, Warren made his first foray into electoral politics, serving as the campaign manager for his friend, Republican Assemblyman Frank Anderson. With the support of Governor Friend Richardson and publisher Joseph R. Knowland, a leader of the conservative faction of San Francisco Bay Area Republicans, Warren was appointed as the Alameda County district attorney in 1925. Warren faced a tough re-election campaign in 1926, as local Republican boss Michael Joseph Kelly sought to unseat him. Warren rejected political contributions and largely self-funded his campaign, leaving him at a financial disadvantage to Kelly's preferred candidate, Preston Higgins. Nonetheless, Warren won a landslide victory over Higgins, taking over two-thirds of the vote. When he ran for re-election again in 1930, he faced only token opposition. Warren gained a statewide reputation as a tough, no-nonsense district attorney who fought corruption in government and ran his office in a nonpartisan manner. Warren strongly supported the autonomy of law enforcement agencies, but also believed that police and prosecutors had to act fairly. Unlike many other local law enforcement officials in the 1920s, Warren vigorously enforced Prohibition. In 1927, he launched a corruption investigation against Sheriff Burton Becker. After a trial that some in the press described as "the most sweeping exposé of graft in the history of the country," Warren won a conviction against Becker in 1930. When one of his own undercover agents admitted that he had perjured himself in