For decades after World War II Nationalist soldier Zeng Hui was ostracised by China's Communist authorities, despite having fought against arch-enemy Japan.

But, at more than 100 years old, he has been brought back into the fold as Beijing seeks unity against Tokyo.

In a wheelchair, military decorations pinned to his chest, the centenarian struggles to list the battles in which he fought against the Japanese in the 1940s. "Songshan," he enunciates at one point.

After WWII, the Nationalist Kuomintang (KMT) army lost China's brutal civil war to Mao Zedong's Communists in 1949. Its chief Chiang Kai-shek fled to Taiwan, along with most of the leadership, but many rank and file such as Zeng stayed behind.

He spent years being persecuted under the Maoist regime, when those declared class enemies faced confinement, beatings and worse. Even now he will not speak of what happened to him.

"My father was a member of the Kuomintang," said his son Zeng Longxiang, 63. "Because of the Cultural Revolution, he dares not speak too much of the battles in which he participated. And we, the children, we never dared to broach the subject."

But in a new era -- Chiang died 40 years ago at the weekend -- Beijing is promoting the Kuomintang veterans as a symbol of the struggles against Japan.

A gold-fringed banner in Zeng's home in Mangshi, deep in the southwestern province of Yunnan, declares him a "pillar of the nation", and a medal pinned to his overcoat is emblazoned: "Hero of the War of Resistance Against Japanese Occupation."

- 'Tooth and nail' -

Japan controlled vast swathes of China, from Manchuria to Indochina, during World War II. By 1938, Chiang's Nationalist government had retreated inland to set up a provisional capital in Chongqing.

With the Nationalists dependent on Allied resupply along the Burma Road or by air over the "Hump" of the Himalayas, Yunnan became a vital strategic lifeline.

The China-Burma-India theatre saw desperate, bloody combat when the Imperial Japanese Army tried to force its way into India, the jewel of the British Empire in Asia.

Conscripted into the KMT army in 1942, Xiang Xueyun was sent to join the Allied efforts. "India was occupied by the Japanese and we fought tooth and nail against them in the jungle," he told AFP.

In Yunnan, it was mainly Chinese Nationalist forces who confronted the Japanese, say veterans and historians.

"The Kuomintang were fighting a real war, while the Communists were more like guerrillas," said Xiang, now 90.

But after the Communist civil war victory, history was rewritten and the role played by the Nationalist army obscured.

Chiang was the first target for vilification.

In his Selected Works, Mao Zedong argues that Communist fighters were "facing enemy lines", while Chiang fled to the remote southwest. At the end of the war, "he descended from his mountain to reap the fruits of victory", Mao wrote.

But in recent years, the propaganda machine has changed course, and at the Kuomintang war cemetery in Yunnan's Tengchong, the headstones of thousands of Nationalist "martyrs" have been restored after being ruined by Mao's Red Guards.

"The city of Tengchong was liberated by KMT troops," said guide Yang Shuangjiao. "The Communists also contributed, but to a lesser extent."

Large photos of Chiang hang in a nearby museum, including an image of the "Generalissimo" toasting with Mao. China's main state television, CCTV, broadcast a report praising Nationalist General Dai Anlan last week.

"Today the Communist Party highlights the united front policy towards the KMT and Taiwan," Jean-Pierre Cabestan, head of the political science department at Hong Kong Baptist University, told AFP.

"Now there is a new amnesia when talking about the fierce struggle Mao led against Chiang between 1927 and 1937, and especially between 1946 and 1949 to establish his dictatorship over the country."

- 'Impress Japan' -

Beijing regularly accuses Tokyo and nationalist Prime Minister Shinzo Abe of refusing to own up to its wartime past. One English exhibit in the Tengchong museum reads: "The Japanese right wing forces are expanding rapidly in Japan. They visit Yasukuni Shrine and keep challenging the international order established after World War II.

"They even want to have a finger on Diaoyu islands belonging to China. Therefore it is quite necessary to alert the revival of the Japanese militarism."

China will hold a rare major military parade this year, with one objective being to "impress Japan", according an editorial in the People's Daily, the official Communist Party mouthpiece.

The Chinese government is trying to "reactivate and strengthen the anti-Japanese sentiments across Asia and among ordinary Chinese," said Cabestan.

But the one place the message might not resonate is Taiwan itself, he added.

The anniversary of Chiang's death passed on the island with barely a ripple. President Ma Ying-jeou visited his mausoleum, but media attention was limited and the Beijing-sceptic opposition is pushing for the statues that marked his authoritarian rule to be taken down.

Most Taiwanese "have feelings of friendship and closeness with contemporary Japanese society", said Cabestan. "The old Nationalist fighters belong to a bygone era."