Apparently those shop window dummies have fought in wars too. Their first recorded use (and probably the most clever) was in ancient China. It’s been recorded in battles like the Battle of Yongqiu.
There, the Tang army (which was under attack) tied scarecrows to rope and lowered them down the walls of the castles. They were instantly targeted by archers. This served two purposes. The first was to lure the fire away from the Tang soldiers, and the second was to replenish the supply of arrows.
Once the scarecrows were full of arrows, they would be pulled back up to the top, and the arrows would be reused by the archers. Mannequins were also used in World War I. World War I, in case you don’t know, was fought in many places with trench warfare, where each side had dug a large trench to stage attacks from. Typically, these battles were ongoing stalemates.
The area between the trenches was called no man’s land, because running into it would be a guaranteed death. Mannequins were then employed to draw sniper fire so that enemy snipers could be targeted or allied units could move more safely.