How do the parachutes falling from the sky illustrate the turning point in the story?

The novel tells the story of occupation and resistance during World War II in an unnamed country (probably Norway). The local people search for ways to resist the control of the occupying army, which is coercing them into mining coal for the war effort. Because they are under surveillance and unarmed, the townspeople decide that dynamite will be the most effective weapon. The parachute scene is the point where their plans start to work out.
Some time after the occupiers kill Alexander Morden, their Lieutenant Tonder develops an interest in Molly Morden, unaware that she is Alex’s widow. Returning at her encouragement, rather than having a romantic encounter, Tonder finds that Molly has a knife. She fatally stabs him. Her decisiveness inspires her fellow residents.
A few locals had managed to escape to England and sought the help of the English forces. Soon after Molly kills Tonder, everyone sees planes overhead. The English fliers drop packages with little parachutes. Along with chocolate and other supplies, they contain sticks of dynamite. With the dynamite, the townspeople step up their actions and blow up a mine.
Even though they are punished for the action, the fact that they banded together to pull it off marks a turning point in morale. The reader is left encouraged in the idea that they will ultimately succeed in driving off the occupiers.