 At a meeting with Mackay on Christmas Eve , 1940 , O 'Connor visited Mackay at 6th Division headquarters and directed him to prepare an attack on Bardia . O 'Connor recommended that this be built around the 23 Matilda tanks of Lieutenant Colonel R. M. Jerrram 's 7th Royal Tank Regiment that remained in working order . The attack was to be made with only two brigades , leaving the third for a subsequent advance on Tobruk . Mackay did not share O 'Connor 's optimism about the prospect of an easy victory and proceeded on the assumption that Bardia would be resolutely held , requiring a well @-@ planned attack similar to that required to breach the Hindenburg Line in 1918 . The plan developed by Mackay and his chief of staff , Colonel Frank Berryman , involved an attack on the western side of the Bardia defences by Brigadier Arthur " Tubby " Allen 's 16th Infantry Brigade at the junction of the Gerfah and Ponticelli sectors . Attacking at the junction of two sectors would confuse the defence . The defences here were weaker than in the Mereiga sector , the ground was favourable for employment of the Matilda tanks , and good observation for the artillery was possible . There was also the prospect that an attack here could split the fortress in two . Brigadier Stanley Savige 's 17th Infantry Brigade would then exploit the breach in the fortress defences in the second phase . Most of the artillery , grouped as the " Frew Group " under British Lieutenant Colonel J. H. Frowen , would support the 16th Infantry Brigade ; the 17th would be supported by the 2 / 2nd Field Regiment . In the event , the artillery density — 96 guns for an attack on an 800 @-@ yard ( 730 m ) front — was comparable to the Battle of St. Quentin Canal in September 1918 , when 360 guns supported an attack on a 7 @,@ 000 @-@ yard ( 6 @,@ 400 m ) front . Mackay insisted that the attack required 125 rounds per gun . It had to be postponed to 3 January in order for this ammunition to be brought forward . 
