A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
A player, 9 July 2007
Reinforce the Gates (U) Coste: 0; Focus: 2. Reaction: After a player announces a Battle action before the Defender’s first normal opportunity to act or pass: Negate the action’s effects. Battle: Even if you control no units at the current battlefield: Target an unopposed unit there. Move the unit to a target battlefield where it would be opposed.
I am the defenser. I have a unit in a battlefield A that has already been resolved.
We are resolving the battlefield B where i have no unit and the attacker has one. Can i play Reinforce the gates to his unit there to move it to the battlefield A ?
The question would be in particular would this unit considered to opposed there.
Chris Fuchs (rules official), 9 July 2007
I am the defenser. I have a unit in a battlefield A that has already been resolved.
We are resolving the battlefield B where i have no unit and the attacker has one. Can i play Reinforce the gates to his unit there to move it to the battlefield A ?
The question would be in particular would this unit considered to opposed there.
Yes. The battlefield still exists, even though it's already been resolved.