The undoubted star of China's giant military parade marking 70 years since Japan's World War II defeat -- and countless television shows on the conflict -- will be the ruling Communist Party, celebrating a victory historians say was largely won by others.

The display will feature 12,000 Chinese troops marching through Tiananmen Square alongside gleaming tanks and missiles, as fighter jets scream overhead.

It will all be overseen by President Xi Jinping -- head of the People's Liberation Army, the ruling party and the government -- in what commentators say is an effort to bend history to bolster the Party's legitimacy.

The parade aims to dramatise "this idea that without the Communist Party, there would be no new China", said Willy Lam, an expert on Chinese politics at the Chinese University of Hong Kong.

"Xi Jinping and the Communist Party wants to claim the credit for vanquishing the Japanese, even though there is a big question mark over this claim," he added.

Tokyo launched a full-scale invasion of China in 1937 and, according to Beijing, the eight bitter years of fighting left 35 million civilians and soldiers dead or injured.

In official materials given to journalists ahead of the event, the Communist Party is described as the "leader" of China's resistance, with its guerrillas fighting "the main form of the war against Japan".

But the major battles in China were fought by the forces of the Nationalist government of the time, led by Generalissimo Chiang Kai-shek, the Communists' bitter enemy.

Mao Zedong's army went on to defeat him in 1949 after a civil war, leaving Chiang exiled to Taiwan.

Ever since, the role of the Nationalists has been largely played down in the official narrative.

For Beijing pastrymaker TT Chen, the Communist Party's distortion of history is an affront to his family -- two of his uncles held senior positions in the Nationalist regime.

"I don't consider the parade patriotic, I think it's a show of ignorance," he said.

- Savage war crimes -

Japanese forces committed savage war crimes that still fuel national resentment, and are regularly highlighted by the Communist Party.

Dramas about the "Chinese People's War of Resistance against Japanese Aggression", as Beijing officially calls the conflict, are a mainstay on Chinese screens, with broadcasts heightened for the anniversary.

By far the majority depict the Communist struggle, although there are tentative nods to the Nationalists' contribution and authorities have now renovated Chiang's residence in wartime capital Chongqing.

Some senior Communist Party members quietly acknowledge the differing take on history.

Li Nanyang's father Li Rui was a secretary to Mao Zedong, and organised Communist soldiers to fight inside a Kuomintang (Nationalist) regiment, under Chiang's ultimate command, in the late 1930s.

But the unit fled just two days later, and Li returned to the Communists' remote mountain headquarters in northern China, where "he didn't do anything to directly attack the Japanese", she said.

"Looking at my father's account, its clear that the war against Japan wasn't led by the Communist Party," she told AFP.

Rana Mitter, an Oxford University historian of the period, estimates that 15 to 20 million Chinese people died in the conflict.

While joint efforts by the Communists and Nationalists staved off defeat, he said, "the international element of Allied assistance was the factor which really tipped the balance towards victory".

- 'Communist propaganda' -

Since coming to power in 2012, Xi has centralised power and cracked down on critics of the ruling party, and Thursday's spectacle will also act as a "coronation", symbolising his position as party supremo, said Lam at the Chinese University of Hong Kong.

"A military parade is a well entrenched political ritual, until a top leader has held the ritual he cannot be an undisputed strongman," Lam added.

For baker TT Chen, the biggest impact will be on his business.

Now 69, he escaped to Taiwan at the age of three with his uncles, who were the core of one of the "four big families" of the Nationalist government.

He returned to Beijing a decade ago to open his bakery, but shops across the capital will close on Thursday, when police will flood the streets -- blocking access to ordinary citizens -- and swathes of the city will be closed to traffic.

"There are so many controls, I will have to close the store," he said.

"China has restored my uncle's old residence, so you can see that the Communist Party has some acknowledgement of the Nationalists. But it's all in the service of Communist propaganda."