http://homepage.ntlworld.com/andrew.etherington/month/thismonth/13.htm
April 13th, 1941
GERMANY: Berlin: The Wehrmacht High Command announced:
Yesterday the Luftwaffe again inflicted heavy losses in repeated raids on the remains of the Serbian army. Dive-bomber, destroyer and fighter aircraft cut enemy march columns to pieces in the lower Bosnia valley and in the area between the Sava and Drin rivers. Ground-attack aircraft bombed military installations around Sarajevo and scored bomb hits on aircraft stationed on the ground at Mostar airfield. Other Luftwaffe formations blew up Greek troop assemblies at Deskati. In the Lake Prespa area, German fighter planes shot down 6 British Bristol Blenheims. In bomb raids on Piraeus harbour, the Luftwaffe sank four merchant vessels totalling 35,000 tons, badly damaged eight large merchant vessels, and set the harbour installations on fire. During the last two nights, heavy calibre bombs hit a destroyer and 3 large merchant ships in the inlet at Eleusis and outside the port of Piraeus. Another effective high-explosive bomb raid was made on Eleusis airfield.
Berlin: Hitler orders swift mopping-up operations in Yugoslavia and Greece.
U.S.S.R.: Moscow: In a treaty designed to safeguard both parties’ borders, the Soviet Union and Japan today signed a neutrality pact, valid for five years.
By acknowledging existing borders the pact, negotiated by Molotov, give Russian recognition to Japanese Manchuria (now known as Manchukuo) for the first time. Under the pact, should either the Soviet Union or Japan become the object of military action, then the other party will observe neutrality.
The impetus came from Russia, increasingly concerned by the deterioration of its relationship with Germany. In Tokyo the pact was welcomed as guaranteeing Japan’s “back door”.
This means that Stalin can begin troop movements east and that Japan can look south.
YUGOSLAVIA: German and Hungarian troops enter Belgrade.
GREECE: General Wilson decides to withdraw to the Thermopylae line - running from the town of Molos on the Gulf of Euboea east of Thermopylae, to Eratine on the Gulf of Corinth.. This is a naturally strong defensive line, and had the merit of being only 50 miles long (compared with the 100 miles of the Olympus-Vermion line) and could in theory be held by the British troops on their own.
MALTA: The island is heavily bombed by the Luftwaffe.
LIBYA: The Germans capture Sollum and Fort Capuzzo.
ATLANTIC OCEAN: AMC HMS Rajputana on Northern Patrol is lost to U-108 in the Denmark Strait.
http://worldwar2daybyday.blogspot.com/
Day 591 April 13, 1941 (Easter Sunday)
Libya. Rommel has finally received 2 maps of Tobruk’s defenses from his Italian allies (he keeps 1 map and gives the other to 5th Light Division commander General Streich). Rommel decides to concentrate his armour and plan an attack on Tobruk in force, using 5th Light plus Italian Ariete and Trento Divisions from the South at dusk. Allied defenders observe the preparations. After an artillery barrage at 5 PM, German infantry advancing at 5.30 are prevented from blowing the wire and filling anti-tank ditches by accurate British artillery fire. German tanks mill around overnight unable to find gaps to penetrate. Further East, Germans recapture Bardia (unopposed) and Fort Capuzzo, pushing the British out of Libya. Fort Capuzzo has now changed hands 4 times since June 1940.
Balkans. Leibstandarte SS Regiment cuts West through the Metsovon Pass to get behind the Greek Army of Epirus, holding the Albanian front. Too late, Greek Coomander-in-Chief General Papagos realizes the danger and orders a retreat (British General Wilson attributes this to a “fetishistic doctrine that not a yard of ground should be yielded to the Italians”). Italians pursue the withdrawal along the entire front, capturing the towns of Korçë, Permet and Porto Palermo on the Mediterranean coast. Further South, Germans bomb the Greek port of Piraeus sinking Greek destroyer Psara and badly damaging destroyer Vasilevs Georgios I.
In Moscow, Foreign Ministers Matsuoka (Japan) and Molotov (USSR) sign a 5 year Neutrality Agreement. With his Eastern border secure, Stalin transfers forces from Siberia to meet a suspected German attack.
U-108 has tracked British armed merchant cruiser HMS Rajputana for 2 days and missed her with the 5 torpedoes. At 7.43 AM 100 miles West of Iceland, U-108 sinks HMS Rajputana with the 6th torpedo (40 killed, 283 rescued by British destroyer HMS Legion and landed at Reykjavik). At 10.29 PM 75 miles West of Sierra Leone, U-124 sinks British SS Corinthic (2 killed, 37 crew and 2 gunners picked up by Dutch tanker Malvina and landed at Freetown).
“Berlin: Hitler orders swift mopping-up operations in Yugoslavia and Greece.”
Thus the seeds of an effective partisan movement are sown in Yugoslavia. While the invasion of Yugoslavia will not delay Barbarossa (as discussed a while back), the looming start date for Barbarossa is pressing Hitler to get his forces out of the Balkans and made available for service in the USSR. The result is that he doesn’t give his armies time to round up all of the Yugoslavian army, and more importantly, to identify and secure all of the Yugoslav weapons and supply dumps.
The rough mountainous terrain will help the Yugoslavs, and because of that the Germans needed to take their time to pacify the country. Getting their panties in a wad to get freed up for Barbarossa wasn’t prudent.