Just my opinion here, but feel pretty confident on this one. I'm sure this will pop up during the tournament, so at least for me, I need to have it clear. During a game this weekend, a couple of assault scenarios caused a bit of an issue. If anyone has any other interpretations I'd love to hear them. I play light infantry companies so the assault is a force multiplier for me. A clear understanding of this concept is a plus.
The assault phase is just that, a phase. All normal movement in the movement phase and all shooting in the shooting phase has already been resolved at this point; prior to the assault phase.
You can move up to four inches away from the enemy in the movement step and NOT assault, not a good move IMHO, but it is the players choice. This is where I used to get confused. Assault phase MUST remain separate from the movement phase.
Base to Base contact is not made during the movement phase, regardless of the players intention to assault or not. Base to base contact between the closest unit is the made during the Assault phase. This makes perfect sense to me as a player may want to soften up the enemy with indirect fire to pin prior to moving into the assault. This would be hard to do if your units are sitting in base to base contact from the movement phase.
Anyone watching the excellent Battlefront videos? This is explained at the very beginning of the first assault video, they state that all other movement and shooting is already complete. I missed that and I've watched that video a dozen times. Don't know if this helps anyone else, but this issue can turn a good game sour really quick.