38°00′18″N 126°47′53″E / 38.005°N 126.798°E / 38.005; 126.798

The battle for Outpost Vegas took place during the Korean War between the armed forces of the United Nations Command (UN) and China from 26 to 30 March 1953, four months before the end of the Korean War. Vegas was one of three outposts called the Nevada Cities north of the Main Line of Resistance (MLR), the United Nations defensive line which stretched roughly around the latitude 38th Parallel. Vegas, and the outposts it supported, Reno and Carson, were manned by elements of the 1st Marine Division. On 26 March 1953 the Chinese People's Volunteer Army (PVA) launched an attack on the Nevada Cities, including Vegas, in an attempt to better the position of China and North Korea in the Panmunjon peace talks which were occurring at the time, and to gain more territory for North Korea when its borders would be solidified. The battle raged for five days until PVA forces halted their advance after capturing one outpost north of the MLR on 30 March, but were repelled from Vegas. The battle for Outpost Vegas and the surrounding outposts are considered the bloodiest fighting to date in western Korea during the Korean War. It is estimated that there were over 1,000 American casualties and twice that number of Chinese during the Battle for Outpost Vegas. The battle is also known for the involvement of Sergeant Reckless, a horse in a USMC recoilless rifle platoon who transported ammunition and the wounded during the U.S. defense of outpost Vegas.

In March 1952, the 1st Marine Division redeployed from east-central to western Korea, to join US I Corps where they were assigned a 35-mile (56 km) sector to defend on the Main Line of Resistance (MLR). The specific sector on the MLR was called the Jamestown Line. This sector was located between PVA forces to the north and the South Korean capital of Seoul to the south. The 1st Division was supported by the 1st Marine Aircraft Wing, who had also been recently deployed to western Korea.

1st Battalion, 5th Marines defended the Nevada Cities, reportedly coined as such by Lieutenant colonel Tony Caputa because "it's a gamble if we can hold them." Lieutenant colonel Jonas M. Platt commanded 1st Battalion, while Colonel Lew Walt commanded the 5th Marine Regiment. The 1st Division's formations from left to right comprised the Republic of Korea Army (ROK) Kimpo Provisional Regiment, 1st Amphibian Tractor Battalion, 1st Marines and the 5th Marines. The 1st Marines had replaced the 7th Marines earlier in March. The 1st Marine Division was supported by separate units of artillery, tanks, and aircraft. The 11th Marines commanded by Colonel Mills provided artillery support. Three of four companies of the 1st Tank Battalion supported with M46 Pattons, flame tanks, and retrievers. The 1st Marine Air Wing, with 6,400 personal located throughout Korea, supported with helicopter evacuations of night frontline combat casualties, artillery spotting flights, airborne control of airstrikes and routine liaison and reconnaissance, administrative, and resupply flights.

Opposing the Marines was the PVA line of formations, from left to right: the 19th Division of the 65th Army, who had three regiments forward; and the 120th Division of the 40th Army (under the control of the 46th Army), who had three regiments forward. According to the 1st Marine Division Diaries, the Chinese were active in patrolling and ambushing in defense of positions during the first part of March. During the last part of March the PVA began "limited objective attacks" against US outposts. These attacks varied from a squad to two battalions in strength against outposts Reno and Vegas, in order to deny the US observation into the PVA rear areas.

I Corps commander General Bruce C. Clarke advocated defense on the hills north of the MLR to deny the tactical advantage they offered to the PVA. Vegas was the highest of the "Nevada Cities" and 1,310-yard (1,200 m) north from the MLR. "From North to South this observation included in its 180-degree sweep, enemy hill mass 57 to the right, friendly outpost Berlin, the MLR, key Marine defense highpoints, Hills 229 and 181 in the 1st Marines sector, and intervening terrain." However, soldiers on Vegas could not see Reno. A rifle platoon of 40 Marines and two Navy corpsmen manned each outpost. 250-yard (230 m) of trench line surrounded the outpost, which ranged from 4–8-foot (1.2–2.4 m) deep. Beyond the trenches two parallel lines of barbed wire lay, linked with more parallel aprons of wire connecting the two, sometimes referred to as the "Canadian system. Outpost Reno, formerly Outpost Bruce, had been the scene of intense fighting from 5–6 September 1952 during the Battle of Bunker Hill and three Marines were awarded the Medal of Honor for their actions there, two posthumously.

The three outposts of Carson, Reno and Vegas differed from one another according to their location, the terrain to be defended, and the threat they faced. Outpost Carson, on the left, guarded a largely barren hilltop where a cave provided living quarters for the Marines, who manned an oval perimeter protected by barbed wire and including bunkers, tunnels and a main trench with fighting holes. Except for the slope nearest the Jamestown Line, where a deeper entrenchment was being dug, the main trench on Carson averaged 5 feet (1.5 m) deep by 2 feet (0.61 m) wide. Most of the 28 fighting holes had excellent fields of fire, though the overhead cover on some of them had reduced the opening for observation and firing. During darkness, two listening posts covered the likeliest avenues of PVA attack, from the Ungok hills to the west and Hill 67 to the north. Reno, in the center, was the most vulnerable of the three. It not only lay closest to PVA lines, but also occupied a ridge that forced the defenders into a perimeter vaguely resembling the wishbone of a turkey, open end to the north. As at Carson, a cave served as living quarters and might also become a last-ditch redoubt. A tunnel provided access to the cave from the main trench, which varied from 5–7 feet (1.5–2.1 m) deep. The Marines at Reno built no bunkers, relying exclusively on fighting holes in the trenches and, as a last resort, the cave itself. Outpost Reno had limited fields of fire in the direction of PVA-held Hill 67, also called Arrowhead Hill, but Outpost Carson, on the left, provided fire support in this area. As a result, the approach that seemed to pose the greatest danger to Reno's defenders followed a ridge extending generally southward from Hill 150. Like the Marines defending the other outposts, those at Reno relied on C-rations and tossed the empty cans into nearby gullies. At night, when the tin cans clattered, the source of the noise might be PVA moving close to attack behind a sudden barrage. To the south of Reno lay Reno Block, an L-shaped trench with a small bunker at the end of the shorter leg and a machine gun position at the point where the legs joined. At night a reinforced squad manned the blocking position, which served as a listening post, helped screen the movement of supplies and reinforcements, and provided a rallying point for relief columns ambushed by PVA patrols. Perched on a hilltop, Reno Block afforded excellent visibility, but conversely it could easily be seen from PVA lines. Marines manning Reno's east–west trench could fire in support of the blocking position, as could the garrison at Carson. To the right of Reno loomed Outpost Vegas, which as the tallest of the three, afforded the best fields of observation. Barbed wire and a well-constructed trench encircled the egg-shaped perimeter on Vegas, with its one warming and two living bunkers. Although the fields of fire on Vegas were less than ideal, handicapped in places by a steeply pitched slope too irregular for grazing fire and also by the small firing apertures in some of the covered fighting holes, weapons there could support Reno with long-range fire. By day, Vegas proved a magnet for sniper fire and harassment by mortars and artillery, forcing the Marines to remain under cover.

UN intelligence did not expect a PVA attack during late March. Winter had turned to spring, and with the change of temperature, the melting snow turned the roads to mud, making logistics near to impossible. The newly deployed 1st Marines expected a comparatively quiet front in western Korea to the fighting they experienced elsewhere.Furthermore, the lines of resistance had for most of the war remained static. There are different reasons for the PVA attack to come on 26 March. According to Elliot Akermann, the Chinese wanted to capture the Nevada Cities north of the MLR in order to gain leverage at the Panmunjom peace talks. If the PVA gained a victory here, they could threaten Seoul, thus embarrassing and putting pressure on the UN negotiators at the talks. For Lieutenant colonel Pat Meid and Major James M. Yingling, the PVA wanted to take the hills and ridgelines adjacent to the Marine MLR. This would then better their position at the peace talks, and solidify captured territory for North Korea after peace was achieved.