But the situation south of the Somme gave cause for the gravest anxiety. The north flank of the French was hourly retiring in a south-westerly direction, and the ever widening gap was filled only by a scratch force of odd units supported and assisted by a few elements of the First Cavalry Division. The right flank of our Third Army, therefore, lay exposed to the danger of being turned, if the enemy should succeed in pressing his advantage as far west as Corbie, and in crossing the river at or west of that town.
It was for this reason that, after a conference with General Congreve, late in the day, I decided to deploy my 9th Brigade along the Somme from Sailly-le-Sec westward as far as Aubigny,[4]—far too extended a front for one Brigade, but at least an effort to dispute the passage by the enemy of the existing bridges and lock-gates over the Somme.
The two following days were full of toil and hard travelling in establishing touch with Divisional Headquarters to the north and south of me, in arranging for co-ordinated action with them, and in gleaning all possible information as to the situation, and as to the number and condition of other troops available in an emergency.
It was an especial pleasure for the Australian troops to find themselves fighting in these days in close association with famous British Cavalry Regiments, and that these feelings were reciprocated may be gathered from the following letter from Major-General Mullens, who commanded the First Cavalry Division, which was devoting its energies to covering the gap between the Somme and the French flank:
"My dear Monash,
"I was hoping to have come to see you, when the battle allowed, to thank you, your Artillery Commander, and your Brigadiers who were alongside of my Division, for your most valuable and encouraging support and assistance, especially on the 30th March, when we had a hard fight to keep the Bosche out of our position. I was very much struck by the courtesy of yourself and your officers in coming to see me personally, and for your own and their keen desire to do everything in their power to help. As you know, we had a curious collection of units to deal with, and it was a very real relief to know that I had your stout-hearted fellows on my left flank and that all worry was therefore eliminated as to the safety of my flanks. Your order for the placing of your heavy guns and batteries so as to cover my front was of very real assistance, and incidentally they killed a lot of Huns, and what they did was much appreciated by us all. Will you convey to all concerned my own appreciation, and that of all ranks of the 1st Cavalry Division. It was a pleasure and an honour to be fighting alongside troops who displayed such magnificent moral. I only hope we may have the chance of co-operating with you again, and under more favourable circumstances.
"Yours sincerely,
(Sgnd.) "R. L. Mullens."
On the night of March 29th I advanced my line, pivotting on my right, until my left rested on the Ancre east of Buire, an extreme advance of over 2,000 yards, meeting some opposition and taking a few prisoners. This deprived the enemy of over a mile of valuable vantage ground on the crest of the plateau along which ran the main road from Corbie to Bray.
Map A.