Define effective. After the Burma road was cut, American aid was flown over the Himalayas. The Republic was pressured by the Americans to contributes forces to a campaign to retake Burma. That campaign was successful, but by the time the Burma Road was reopened the Himalayas was the more practicable.

The Republic of China took significant casualties opening Burma. And these were some of their best troops.

It is often suggested that troops controlled by the CCP were more effective against the Japanese. The Republic of China is often criticized for devoting some of their best trained and best equipped units to containing the Communist threat.

Indeed, a significant number of American officials accused the ROC of not fighting. China's war effort nevertheless tied down a million Japanese troops. America's war in the Pacific would have been very different if the ROC had gone Vichy.

Despite this fact, aid was often not distributed because of China's perceived lack of effort.

The Communists did resist. You cannot take that from them. They, however, did not bare the greater burden. They did, however, play a pivotal role in rescuing American airmen shot down over enemy territory. This role was not reported at the time. It did however buy them a lot of good will. A sizable group of American officials and journalists presented the Communists as patriots that merely desired a bit of sensible land reform.

And of course aid was misappropriated.

China: 1945 is a good book on this subject.

I will not say the Republic of China was perfect. How private soldiers were treated. The ROC's deliberate flooding of the Yellow River to buy more time to defend Wuhan. 500,000 drowned. Millions displaced. How Changsha was needlessly torched in a panic.

But I will say that the Republic of China contributed more to the war effort than most people think. American aid was crucial to this. American advice, however, cost the ROC dearly.