This is personification. It means that human qualities are attributed to non-human entities. Here it says that the contemporary frustration nourishes the movement, which is a personification.
They cover his eyes while it happenig
In Flanders fields the poppies blow
Between the crosses, row on row,
That mark our place; and in the sky
The larks, still bravely singing, fly
Scarce heard amid the guns below