Editing Fort Mills (section)

===The siege begins===
The [[Imperial Japan|Japanese]] invaded northern [[Luzon]] a few days after the [[attack on Pearl Harbor]] on 7 December 1941 that brought the US into the war. They advanced rapidly, with other landings elsewhere, notably at [[Legazpi, Albay|Legazpi]] in southeast Luzon on 12 December, [[Davao City|Davao]] on Mindanao on 20 December, and [[Lingayen Gulf]] on 22 December. On 26 December 1941 Manila was declared an [[open city]], with the Philippine government and MacArthur's headquarters evacuated to the Malinta Tunnel. Amid the evacuations, a re-inauguration ceremony for Philippine President [[Manuel L. Quezon|Manuel Quezon]]'s second term was held just outside the tunnel on 30 December.<ref>Morton, pp. 491-492</ref> The Japanese entered Manila on 2 January 1942.<ref>Morton, pp. 232-238</ref> Five days later the U.S. and Philippine forces completed a fighting withdrawal to the [[Bataan]] peninsula, northwest of Corregidor, and prepared to defend it. In the northern Philippines, this left only Bataan, Corregidor, and Forts Hughes, Frank, and Drum in Allied hands.<ref>Morton, pp. 230-231</ref> This situation had been anticipated in the prewar [[War Plan Orange]]-3, under which the forces in the Philippines were expected to hold out at the mouth of Manila Bay for six months. By that time it was anticipated that a relief expedition from the U.S. might arrive. General MacArthur had hoped to defend the Philippines more aggressively under the Rainbow Plan, and was able to get some reinforcements in the months prior to the U.S. entering the war, but this fell apart with the rapid Japanese advance in December 1941. And, with almost all of the Pacific Fleet's battleships sunk or damaged at Pearl Harbor, and the Japanese advancing in several parts of Southeast Asia at a much greater rate than expected, no relief was organized. Although extensive [[Philippine resistance against Japan|guerrilla operations]] were conducted by Filipinos with U.S. support, U.S. forces did not return to the Philippines in strength until the [[Battle of Leyte|invasion of Leyte Gulf]] in October 1944.<ref name="Morton, pp. 61-70">Morton, pp. 61-70</ref>

One aspect of MacArthur's Rainbow Plan was the Inland Seas Project, intended to defend a shipping route to keep his forces supplied. Part of this was a buildup of [[Philippine Commonwealth Army|Philippine Commonwealth]] forces, and a projected deployment of [[coastal artillery|coast artillery]] weapons manned by them in the central Philippines. In 1940-41 eight [[8-inch M1888|{{convert|8|in|0|adj=on}} railway guns]] and 24 [[155 mm gun M1918|{{convert|155|mm|1|abbr=on}} GPF guns]] were delivered to the Philippines, without crews as they were to be locally manned. The 8-inch guns were sent north in December 1941 to engage the invading Japanese forces, but six of them were destroyed by air attack. One gun was eventually placed on a fixed mount as Battery RJ-43 on Corregidor in March 1942; the other may have been at [[Bagac, Bataan]]. Reportedly the Corregidor gun fired only five proof rounds, then went unused for lack of a crew until knocked off its mount by bombing or shelling. The history of the Bataan gun is unknown. Most or all of the 24 155&nbsp;mm GPF guns were eventually deployed at Corregidor and/or Bataan.<ref>[http://corregidor.org/chs_bogart/bogart3.htm The Doomed Philippine Inland Seas Defense Project]</ref><ref>[http://corregidor.org/chs_bogart/bogart3a.htm Account of the 8" railway guns in the Philippines, 1940-42]</ref>