The Battle of the Border begun around 05:00 hours as German troops started crossing the Polish border in numerous places. The Battle of Westerplatte, which is often described as having begun as 04:45 with the salvos of SMS Schleswig-Holstein on Polish coastal fortifications, is commonly described as the first battle of the war. Other sources have described the 04:45 salvos as happening "minutes after Luftwaffe attacks on Polish airfields". Several historians identify the first action of the war as the bombing of the key Tczew bridge in the Polish Corridor by dive bombers from Sturzkampfgeschwader 1 around 0430. Polish historian Jarosław Tuliszka noted that a number of German units started hostilities across the border before shots were fired at Westerplatte. False flag Operation Himmler has begun hours earlier.