Cavalrymen were equipped with sabres and pistols or carbines; light cavalry were used principally for reconnaissance, screening and tactical communications, while heavy cavalry were used as tactical reserves and deployed for shock attacks. Smoothbore artillery provided fire support and played the leading role in siege warfare. Strategic warfare in this period centred around control of key fortifications positioned so as to command the surrounding regions and roads, with lengthy sieges a common feature of armed conflict. Decisive field battles were relatively rare, though they played a larger part in Frederick's theory of warfare than was typical among his contemporary rivals. The Silesian Wars, like most European wars of the eighteenth century, were fought as so-called cabinet wars in which disciplined regular armies were equipped and supplied by the state to conduct warfare on behalf of the sovereign's interests. Occupied enemy territories were regularly taxed and extorted for funds, but large-scale atrocities against civilian populations were rare compared with conflicts in the previous century. Military logistics was the decisive factor in many wars, as armies had grown too large to support themselves on prolonged campaigns by foraging and plunder alone. Military supplies were stored in centralised magazines and distributed by baggage trains that were highly vulnerable to enemy raids. Armies were generally unable to sustain combat operations during winter and normally established winter quarters in the cold season, resuming their campaigns with the return of spring. The Prussian army had massed quietly along the Oder during early December 1740, and on 16 December, without a declaration of war, Frederick moved his troops across the frontier into Silesia. The Prussian force consisted of two corps totalling 27,000 soldiers, while Silesia was defended by an Austrian garrison of only 8,000 men. The Austrians were only able to offer light resistance and garrison a few fortresses; the Prussians swept through the province, taking control of the capital at Breslau without a fight on 2 January 1741. The fortress at Ohlau was also taken without resistance on 9 January, after which the Prussians used it for their winter quarters. By the end of January 1741, almost the entirety of Silesia had come under Prussian control, and the remaining Austrian strongholds of Glogau, Brieg and Neisse were besieged. After leaving winter quarters in early 1741, the Prussian forces began a spring campaign, and on 9 March Prince Leopold II of Anhalt-Dessau took Glogau by storm. In late March, an Austrian force of around 20,000 under the command of Wilhelm Reinhard von Neipperg crossed the Sudetes mountains from Moravia and broke the siege of Neisse on 5 April, after which the main Prussian force manoeuvred to oppose its advance.