The battle on the island was only a fragment of the laarger campaign that was going on in the South Pacific. The other land battle was on New Guinea, however the two gorund fights were the anchors around which the critical air and naval battles revolved.

Over a five to six month campaign the Japanese air and naval offensive power was wrecked. The attrition of IJN aircraft and pilots greatly exceeded the single battle at Midway, the cumalative loss in naval surface power was critical. By the end of the campaign the Japanese Navy had lost its offensive edge and the stratigic intitiative.

Had the Japanese captured the airfield and forced the US to withdraw the overall campaign would have continued. There was still the Australian corps fighting for New Guinea, and the US had prepared other air and naval bases further est and south of the Solomons. While the Japanese would have had a tactical or opertional advntage with its airfield on Guadacannal, exploiting this would have required further offensive action against the other Allied island bases to the south and east. Thus the attritional battles would have continued. The Japanese lines of communication would have been streatched further and rendered more vulnerable to USN raids.

To have won the 'Guadacannal' battle the Japanese Navy would have had to consistently win nearly every naval & air engagement of the summer & autum of 1942. Just capturing the island was not enough. They had to retian a constintly high and favorable attrition rate vs the USN and Allied airforces inthe South Pacific. This would include securing all of New Guinea as well.

It is possible for the Japanese Army to capture Henderson Field and the Japanese navy to lose the campaign and the war if the aircraft and naval losses are still excessive. The Army garrison on Guadacannal would then become another isolated post slowly dying from malnutrition and disease, much like the 110,000 soldiers on Rabul, or the many other bypassed garrisons.

Conversely it was also possible for the Japanese Navay to win this campaign even if the Army does not overrun the airfield. Yamamoto hestated to throw the full weight of the Japanese Navy into the Solomons campaign early on. There were many issues of supply, and replacing losses of the Coral Sea and Midway battles. So he took half measures. Had his staff sucessfully resolved the logistics problems it is possible the Allied Guadacannal & Port Morsby defenders would be isolated, starving, and ineffective instead.

Tikilal's remark about a change in US strategy is valid. Had there been further setbacks in the South Pacific MacAurthers claims for his strategy would have been discredited. King may have then prevailed on Roosevelt to order the concentration of resources in the Central Pacific.