assault. When night falls, the armoured formations turn south in a sweeping move around the southern end of the Gazala line. Battle of Bir Hakeim: The Free French and British troops slow the German advance in North Africa. The Anglo-Soviet Treaty of 1942, to help establish a military and political alliance between the USSR and the British Empire, is signed in London by foreign Secretary Anthony Eden and Soviet foreign minister Vyacheslav Molotov. May 27 – WWII: Operation Anthropoid: Czech paratroopers attempt to assassinate Reinhard Heydrich in Prague, and succeed in wounding him. May 29 – Thai spelling reform of 1942 is initiated by the government of Prime Minister Field Marshal Plaek Phibunsongkhram with his office announcing a simplification of the Thai alphabet. The announcement is published in the Royal Gazette on June 1. The reform is canceled by the government of Khuang Aphaiwong on August 2, 1944. May 30–31 – WWII: Bombing of Cologne – British RAF Bomber Command's "Operation Millennium", its first "1,000 bomber raid", with associated fires make 13,000 families homeless and kills around 475 people, mostly civilians; 3,330 non-residential buildings are destroyed. May 31–June 1 – WWII: Attack on Sydney Harbour: Japanese midget submarines infiltrate Sydney Harbour in Australia, in an attempt to attack Allied warships. June June 1 – WWII: Mexico declares war on Germany, Italy, and Japan. The Grand Coulee Dam is finished on the Columbia River. June 4 – WWII: Reinhard Heydrich succumbs to wounds sustained on May 27, from Czechoslovakian paratroopers acting in Operation Anthropoid. June 4–June 7 – WWII: Battle of Midway: The Japanese naval advance in the Pacific is halted. June 5 – WWII: The United States declares war on Bulgaria, Hungary, and Romania. June 7 – WWII: Siege of Sevastopol: German forces of the 11th Army under General Erich von Manstein begin renowned infantry attacks against the fortress city of Sevastopol. The Germans advance cautiously behind air and artillery support. Manstein had enough firepower to destroy the Soviet fortifications, he has some 1,300 guns and Heavy Artillery Battalion 833 (including a Karl-Batterie with three howitzers of 54 cm nicknamed "Thor", "Odin" and "Loki"). Firing in support, the German 80 cm Schwerer Gustav railway gun fires seven shells. Japanese forces invade the Aleutian Islands (the first invasion of American soil in 128 years). June 8 – WWII: Attack on Sydney Harbour: The Australian cities of Sydney and Newcastle are shelled