Dislocation multiplication from initial sources results in development of a dense dislocation network. Crystals containing dislocations sources (loops) are subjected to uniaxial compression along the axis at a constant true straining rate. The simulation volume contains about 268 million atoms of tantalum. The video sequence progresses through extension of the initial hexagon-shaped loops, to dislocation collisions resulting in the formation of dislocation junctions, to an increasingly dense dislocation network. Green lines represent dislocations and pink lines depict junction dislocations.