The landings at the Lingayen Gulf on 9 January were carried out by the 6th Army under the command of General Walter Krueger. Approximately 175,000 troops from the 6th Army landed along the beachhead within a few days, while the I Corps protected their flanks. XIV Corps under General Oscar Griswold then advanced south toward Manila, despite Krueger's concerns that his eastern flank was unprotected and vulnerable if the Japanese forces attacked. However, no such attack occurred, and the U.S. forces did not meet much resistance until they reached the Clark Air Base on 23 January. The battle there lasted until the end of January, and after capturing the base, XIV Corps advanced toward Manila.