A batchall is issued to determine what forces will be commited to an assault.
What you're refering to is a Trial of Posession/Grievance.
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the Inner Sphere is no stranger to mechwarrior duels, most mechwarriors being at least minor nobility in a feudal system after all.
First Hidden War (Star League Era): minor victory for House Kurita vs. Star League Defence Force.
The First Hidden War was the entire cause for the SLDF to create the Gunslinger program.
Fun thing is, I could see this happening again in 3085 due to Stone's disarmament program.