This improvement in internal affairs helped the Republic overcome the difficult years of the sharpest economic warfare phase. During the lull in the military pressure by Spain after the fall of Breda in 1625, the Republic was able to steadily increase its standing army, owing to its improved financial situation. This enabled the new stadtholder of Friesland and Groningen, Ernst Casimir, to recapture Oldenzaal, forcing the Spanish troops to evacuate Overijssel. Diplomatically, the situation improved once England entered the war in 1625 as an ally. Frederick Henry cleared the Spaniards from eastern Gelderland in 1627 after recapturing Grol. The Dutch victory in the Battle in the Bay of Matanzas in 1628, in which a Spanish treasure fleet was captured by Piet Pieterszoon Hein, contributed even more to the improving fiscal situation, at the same time depriving Spain of much needed money. However, the greatest contribution to the improvement of the Dutch position in 1628 was that Spain had overextended itself again when it participated in the War of the Mantuan Succession. This caused such a depletion of Spanish troops and financial resources in the theatre of war in the Netherlands that the Republic for the time being achieved a strategic superiority: the Army of Flanders declined to 55,000 men while the States Army reached 58,000 in 1627.