It appears that the Earl of Buchan had finally stirred himself to action and was moving against Robert’s Garioch base of operations with a force of around 1000 men. The composition of the force is unclear, but based on subsequent events; it would appear that most of the troops were of inferior quality. We do know the Earl was accompanied by David de Brechin and John de Moubray.
Meanwhile Robert’s force was at Inverurie, possibly at the Bass, which was the site of an older Motte and Bailey. http://en.wikipedia.org/wiki/Motte_and_Bailey
For a modern view see Colin Smith’s picture on the Geograph site http://www.geograph.org.uk/photo/117762
Some accounts have the Earl’s force camping within the remains of a prehistoric hill fort on the summit of Barra hill, which still bears the name “Comyn’s Camp”.
For detailed location, see entry on Geograph site. http://www.geograph.org.uk/photo/671088
Whether this is fact or fiction is not clear, but what is known is that the Earl’s force was in the vicinity of the present day town of Oldmeldrum.
The engagement was opened by a clash between a mounted force under the command of David de Brechin, and the pickets of Robert’s force. It is not clear whether this was a reconnaissance in force which was deliberately seeking the enemy, or a chance encounter. Sir David’s men “ran into” the royal pickets, and drove them back onto the main force, he was then either driven off by or chose to retreat in the face of Robert’s main force. This is often portrayed as an initial defeat, but it shows that Robert had learned from Methven, where the royal army was surprised and routed. At Inverurie the pickets were deployed and performed their function, by allowing the main force time to assemble, forcing Sir David to retire.
Barbour tells us that the impudent attack caused the King to rise from his sick bed and lead his army to Barra.
Yhis, ‘said the King, ‘withoutyn wer,
Haiff coveryt me as thai haiff done.
I sall other haiff thaim or thai me’.
their insolence has made me hail and sound
For no medicine could have made me
Recover as quickly as they have done.
So as God is my witness,
I shall either have them or they me.
Barbour's The Brus - Lines 231 to 236
From the Canongate 1997 Edition: Edited by A.A.M. Duncan