The sounds of footsteps approaching can tell that the people approaching them are not just few people.
Xavier was waiting for the right moment so that they will start attacking the people without making them advance towards the Southern Country.
'After all Xander did give the strategy to the Southern Country so that could withstand this attack. Why not help from our side a bit?'
The people came on walking as if they would never end. At this point Xavier realizes that everyone of them are soldiers. Not a mere unorganized group of extremist people.
Xavier who was expecting more people was not expecting a battalion of soldiers to enter the Southern Country in disguise.
'How could some small group of rebellions have such number of people?!'
He looks at Xander confused only to see him observing everything so calmly. Calm as breeze... not an inkling of impulsiveness.