Italian preparations After the encirclement of Tobruk, Graziani informed Mussolini that Graziani informed Mussolini that the -long Tobruk perimeter was manned by only 22,000 men with 340 guns, a number wholly inadequate for the task. On 9 January, Graziani informed the garrison commander, General
Enrico Pitassi Mannella, that there would be no attempt at relief. Graziani ordered Tellera to fall back with the
60th Infantry Division "Sabratha", his last division, to a line between
Derna and
Berta, while directing the
Babini Group (Special Armoured Brigade) to
Mechili. After being informed by Graziani that he was on his own Mannella had the bridge at Sidi Daud on the Bardia road and the bridge at Wadi es Sahel on the Derna road destroyed.
Order of battle Tobruk garrison Details taken from Montanari (1990) unless specified. •
XXII Corps headquarters (
Enrico Pitassi Mannella) •
61st Infantry Division "Sirte" • 69th Infantry Regiment (3 × battalions, 1 × battery with
65/17 mod. 13 mountain guns) • 70th Infantry Regiment (3 × battalions, 1 × battery with 65/17 mod. 13 mountain guns) • 43rd Artillery Regiment, 2 × groups with
75/27 mod. 06 field guns, 1 × group with
100/17 mod. 1914 howitzers • LXI Machine Gun Battalion • LXI Mixed Engineer Battalion • LXI Replacements Battalion • 51st Bersaglieri Motorcycle Company • 61st Anti-Tank Company, with
47/32 mod. 1935 anti-tank guns • 61st Mortar Company, with 81 mm mortars •
4th Tank Infantry Regiment • I Medium Tank Battalion, with
M11/39 tanks • LXIII Light Tank Battalion, with
L3/35 tankettes • 10th Army Corps Artillery Regiment • 22nd Army Corps Artillery Regiment • 25th Army Corps Artillery Regiment • Blackshirt Battalion (Libyan Volunteers) • CXL Blackshirt Battalion • 22nd Bersaglieri Motorcycle Company • 25th Anti-Tank Company, 47/32 mod. 1935 anti-tank guns • 141st Mortar Company, with 81 mm mortars • 142nd Mortar Company, with 81 mm mortars • 55th Signal Company •
Royal Italian Navy: •
San Giorgio (cruiser) • • Infantry: 2,300 men • Artillery: 2 × groups • Service, quartermasters and supply units Although Pitassi Mannella had thirty-two L3/35 tankettes and thirty-nine M11/39 tanks, only seven of the latter were operational and in three weeks of attempts to repair the M11/39s only three were serviceable enough to move in an engagement. After it had become obvious in the autumn of 1940 that the L3/35 was obsolete and the M11/39 badly designed and prone to break down, the XXI Light Tank Battalion and part of the I Medium Tank Battalion had departed for
Benghazi to be re-equipped with the new
M13/40 tank. Pitassi Mannella had received no spares or fuel for the tanks and had the lightly armed and thinly armoured L3/35 and the M11/39s buried in the sand as strong points.
Fortifications Pitassi Mannella divided the defensive perimeter in two sectors, five sub-sectors and 16 strong points. •
Eastern Sector (Brigadier Umberto Barberis) • Sub-sector A, from the sea to Bir Junes to block the road from Bardia, with four strong points • Sub-sector B, to block the road from
El Adem, with two strong points The first line of the Eastern Sector was manned by the troops of the reinforced with four companies from the 69th Infantry Regiment. Expecting the main attack from this direction, Pitassi Mannella established a second line of defence behind the strong points, based on a small hill at the junction of the
El Adem and Bardia roads. At the second line under command of the 4th Tank Infantry Regiment, every available tank was dug in as a strong point. Between this position and the sea the III Battalion, 69th Regiment dug in. •
Western Sector (Brigadier Vincenzo dalla Mura) • Sub-sector A, in the desert to the South of Tobruk with four strong points • Sub-sector B, to block the road from
Acroma, with three strong points • Sub-sector C, to block the road from
Derna, with three strong points Sub-sectors A and B were defended by a battalion each from the 70th Infantry Regiment, while Blackshirt Battalion (Libyan Volunteers) manned sub-sector C. Behind the first line of defence were five strong points manned by the III Battalion, 70th Infantry Regiment which doubled as the reserve unit for the three battalions in the first line. The commander of the 69th Infantry Regiment received the reserves Pitassi Mannella could muster, an understrength tank company with seven M11/39s and two ad hoc formations, consisting of one Motorcycle company, one infantry company, one machine gun platoon, an anti-tank platoon and an anti-aircraft section each. In front of the strong points of anti-tank ditch was cleared out, 7,000 tripwire mines and 16,000 pressure mines laid. To make up for the lack of
anti-tank mines Pitassi Mannella had 2,200 bombs and 800 bombs, left behind by the (Royal Italian Air Force), buried upright in the desert, in the hope that a British tank passing over them would trigger the impact fuze.
Artillery Pitassi Mannella organised the artillery into three groups, two for the Eastern Sector with 123 guns and one for the Western Sector with 97. Assuming (correctly) that the Commonwealth troops would attack from the south, Pitassi Mannella sent the II/43rd and III/55th groups with 75/27 mod. 11 field guns, and the CV/25th and CXXX/25th groups with
149/13 mod. 14 heavy field howitzers and the 2nd Battery of the XV Group with
75/46 mod. 34 anti-aircraft guns (used as anti-tank guns) into that area. For long-range artillery-fire, Pitassi Mannella relied on the cruiser
San Giorgio in Tobruk harbour which had two twin EOC 10-inch /45 naval gun|/45 guns and four twin Cannone da 190/45|/45 guns. Two (
Royal Italian Navy) shore batteries had twin QF 4.7-inch Mk I – IV naval gun|/40 naval guns and two mobile
149/35 heavy guns of the . With no air reconnaissance, Pitassi Mannella was unaware of the British artillery positions and as most British artillery had a longer range than the Italian artillery, mostly of
First World War-vintage there, was little chance of effective counter-battery fire. Pitassi Mannella decided to employ every gun capable of
direct fire as anti-tank artillery and managed to assemble 110 anti-tank guns; thirty-two 37 mm guns in the buried M11/39s, forty-three 47/32 mod. 1935 anti-tank guns, thirteen 65/17 mod. 13 mountain guns, eleven 75/27 mod. 11 field guns, ten
77/28 mod. 5 field guns and one
76/40 mod. 16 naval gun (found in the naval stores); armour-piercing ammunition was available only for the 37 mm and 47 mm anti-tank guns.
British preparations After surrounding Tobruk, the WDF had exhausted the ample Italian supplies captured at Capuzzo and Sollum; O'Connor directed that the supplies flowing through the port of Sollum ( per day in early January and daily late in the month) to the 10th and 11th Field Depots he had set up about east of Tobruk. Concerned mostly about not having enough fuel and supplies for the offensive after the fall of Tobruk, O'Connor delayed the attack to accumulate more supplies. As the 7th Armoured Division had suffered more losses than the 6th Australian Division, O'Connor decided that the Australians would lead the attack. The two most depleted units, the
8th King's Royal Irish Hussars and the
6th Royal Tank Regiment, were withdrawn and their equipment distributed to the other four regiments of the armoured brigades. The first wave of the attack was to be the 16th Australian Brigade and the
7th Royal Tank Regiment, followed by the
17th Australian Brigade and the 19th Australian Brigade. The 7th Armoured Division would attack along the Western and perimeter to pin down the defenders. On 19 January the
Royal Air Force (RAF) dropped leaflets calling on the Italians to surrender but Mannella took no notice. == Attack ==