What is the 1-3-3-1 Rugby Attacking System?

There are a number of different attacking structure's that are used within rugby, one of those being the 1-3-3-1. This structure is the pattern of forwards across the rugby pitch creating different pods and attacking options. The aim of the structure is to create 12 attacking threats at all times to provide the most effective attack.
Have a watch of the video and let me know what you think of the system and whether you think there are any better attacking systems out there!