At dawn on the 20th, Bevern crossed the border into Bohemia at Gränstein. Malachowsky with 8 squadrons had crossed the border earlier and encountered an Austrian outpost near the small town of Friedland. Though both sides were evenly matched and neither could effectively deploy due to the constrictive nature of ground. After a full morning of skirmishing and feign charges, Beck’s squadrons slowly retired, as in the distance long dark columns could be seen slowly threading their way toward Friedland.
Bevern’s orders were clear, seize as many forward depots as possible and join with Schwerin on the 24th. Together, they would move on Prague while capturing the larger magazines at Jung Bunzlau. Resistance would be expected to be light as Schwerin, with a larger force had crossed the Riessen Gebirge two days earlier. Any determined stand by the Austrians would be threatened with encirclement by Schwerin. Together, they were to meet the King at Prague at the end of April or the first week of May.
Even as late as the middle of April, preparations were made for the large scale raids in Lusatia by Konigseck, but that had all changed with the communiqué he held in his hand. The Prussians had invaded Bohemia. Schwerin had moved across the border on the 18th , but Bevern had not stirred.
Konigseck firstly, strengthened Beck’s force at Friedland (10 squadrons) with an extra two battalions of Grenzers. They would not engaged the Prussians, but determine how large a force they had. Friedland was too far forward to make an effective stand, so Reichenberg was chosen, not only to move the supplies gathered there to the safety of Prague, but the surrounding hillside and woods offered a natural defensive position. The main objective now was to slow Bevern’s advance, save as much supplies that had been gathered and hopefully join Serbelloni. O’Donnell’s Brigade of Dragoons which had served as a link between their two forces had been recalled and would be expected in Lindenau on the 21st. However, Koningseck thought it prudent to leave Wolfersdorf’s squadrons to keep a watchful eye for Schwerin's expected arrival near Gitschin .