What was the biggest movement during the Qin Dynasty, and what was the date?

It must be the construction of the Terracotta Army. It is really a grand work. Starting in 246 BC, it took 39 years to complete, and millions of labors were recruited to build it.

That was just before he died, I would say it was the Great Wall

It would be when he unified all of china in 221 bc

I would say that during the Qin Dynasty 3 major movements were accomplished during the ruling period of Qin Shi Huang's life time including; the Great Wall Of China(c. 259-210 B.C.), the Terracotta Army(259 BC – 210 B.C) and Uniting China(221 B.C), but all of his achievements couldn't have been achieved without millions of deaths causing the vast majority of china to be scared and frightened of him.

There are so many different things,I do not actually think that you could choose. He created the first unified empire, had only one language, used one form of currency, built the Great wall of China, the Terra Cotta army,and so many others. This could not have happened, though, if he had not killed so many peasants and people along the way.

He did several acts/movements as the first emperor of China, uniting it into a country, building he first Great Wall, and building his tomb (the terra cotta army).