After joining (formally) World War Two in the wake of Pearl Harbor, the United States endured a series of defeats at the hands of the Japanese. The Philippines garrison fell, Wake Island fell, Guam fell. British possessions in Southeast Asia teetered and fell as well – the campaign was not going well for the Allies.
The first American offensive of the war would come on August 7th, 1942 with the landing of the 1st and 5th Marines at Red Beach on Guadalcanal. Part of a multi-prong assault (the nearby Japanese bases on Tulagi and Gavutu/Tanambogo were also captured at the same time), the attack on Guadalcanal was made to secure the airstrip under Japanese construction there. If the island became an operational Japanese air base, Allied supply shipping to Australia would come under threat, and this could imperil the whole area of operations.
Fortunately for the Marines, US intelligence massively overestimated the Japanese force on Guadalcanal. It was in fact only a few hundred infantry, leading a work force of about 3,000 laborers (mostly Koreans). They though the US landings were just a small raid, and dispersed into the jungle to wait for the US departure. Instead, the Marines were there to take the airfield and hold it. They were not, however, very well prepared. The Navy suffered a massive defeat in the waters off Guadalcanal the very next night, and would pull out of the area August 9th, leaving the Marines with dangerously low supplies of food, ammunition, and other essentials.
My trip to Guadalcanal was made possible by War Historian Battlefield Expeditions. If you are interested in seeing sights like these in person yourself, check out their upcoming schedule: