The purely economic crisis represented by the depression of 1620 was exacer-bated by a series of political problems which probably further undermined Polish purchasing power. Whatever the ultimate effects of the Polish–Ottoman war, the English government felt that it was in its interest to mediate in the dispute and Sir Thomas Roe was sent to the Sublime Porte to assist in restoring peace to southeastern Europe.

While Poland was engaged in defending its southern frontiers, Sweden used the opportunity to overcome the weakened Polish defences in Livonia. The key to the province was Riga which fell after a brief siege, while European opinion generally condemned the cynicism of Gustav Adolf in taking advantage of Poland's difficulties with the enemies of Christendom. James wrote a letter to the Swedish king urging him to abstain from an attack on Poland which in the event would be unworthy of a Christian ruler, and similar sentiments were echoed even by other Protestant princes. With the fall of Riga, there was little the Poles could do to stem the inexorable Swedish advance and within a few years the province was almost entirely in Swedish hands. Livonia itself was at this time of only limited importance in the commerce of the Baltic, but its conquest merely whetted Gustav Adolf's appetite for the more lucrative trade of the Prussian coast.

The worst effects of economic depression were over by 1624. From 1621 poor harvests in England stimulated demand for Polish grain and, with this return commodity now marketable, English shipping through the Sound rose appreciably, as can be seen in table 9.7 (pp. 170–1).