19 April 1941
Gruppe Herff reported during the morning weak reconnaissance pushes with tanks and artillery against the western flank of its position, and a bombing attack on Kradschtz. Batl. 15. During a visit to Gruppe Herff, Lt. General Rommel instructed that Bardia had to be absolutely occupied by a German company again, and firmly held.
The 10.5cm artillery battalion Frongia was subordinated to Gruppe Herff, and its arrival ordered for 20 April.
Colonel Freiherr von Esebeck reported to the Commander and took over command of all the elements of 15.Panz.Div. already arrived in front of Tobruk.
During the night 18/19 April heavy enemy air attacks on Tripoli and Gazala airfield. During the day again heavy bombing and strafing attacks on army units. Three Hurricanes attacked Gazala at low level, and destroyed one Ju 52 and three Hs 126 on the ground. Two bombing raids on Derna airfield without success.
During the first operation of four Me 109 of Jagdgeschwader 27, at midday on 19 April, it succeeded in shooting down four Hurricanes. One Me 109 had to force land in our territory. AA artillery of Div.Brescia shot down one loaded English bomber during the afternoon. 
A JG27 Me 109E-4 Tropisch off the North African coast, 1941. The E-variant could be distinguished by the straight wing-ends. These were rounded with the F-variant which entered the theatre from October/November onwards. Source: Wikipedia.
This was Rommel’s reaction to the move to reduce exposure of troops to naval artillery fire.
Probably 105/28 corps artillery guns, a World War I design that continued to soldier on during the war.
Freiherr von Esebeck was commander of 15. Schuetzenbrigade, the infantry brigade of 15.Panz.Div., and thus the logical choice to replace General von Prittwitz and Gaffron. He later rose to General der Panzertruppen, and participated in the conspiracy against Hitler. He ended the war in a concentration camp, and died in poverty in 1955. See this link.
Could have been Blenheim Mk.IV V5438 operating out of Fuka (LG17) with No. 45 Squadron R.A.F., which was however reported lost on operations against Bardia and El Adem on 18 April, reported shot down over Cyrenaica. The crew of three, consisting of F/O H.D.Jones, and Sgts. J Webb and H Keen, were all killed.