Meanwhile, the French Revolution alarmed the ruling monarchs of Europe, and in August 1791 Frederick William, at the meeting at Pillnitz Castle, agreed with Emperor Leopold II to join in supporting the cause of King Louis XVI of France. However the king's character and the confusion of the Prussian finances could not sustain effective action in this regard. A formal alliance was indeed signed on 7 February 1792, and Frederick William took part personally in the campaigns of 1792 and 1793, but the king was hampered by want of funds, and his counsels were distracted by the affairs of a deteriorating Poland, which promised a richer booty than was likely to be gained by the anti-revolutionary crusade into France. A subsidy treaty with the sea powers (Great Britain and the Netherlands, signed at The Hague, 19 April 1794) filled Prussia's coffers, but at the cost of a promise to supply 64,000 land troops to the coalition. The insurrection in Poland that followed the partition of 1793, and the threat of unilateral intervention by Russia, drove Frederick William into the separate Treaty of Basel with the French Republic (5 April 1795), which was regarded by the other great monarchies as a betrayal, and left Prussia morally isolated in the struggle between the monarchical principle and the new republican creed of the Revolution. Although the land area of the Prussian state reached a new peak under his rule after the third partition of Poland in 1795, the new territories included parts of Poland such as Warsaw that had virtually no German population, severely straining administrative resources due to various pro-Polish revolts; it also removed the last remaining buffer state between Prussia and Russia.