Nicholas had picked a wolf-and-lamb quarrel with the Porte, of which the ostensible ground was the protection of subjects professing the Greek Catholic faith in the ‘holy places;’ and little expecting, perhaps little caring, that he would arouse the jealousy of France and England, he had sent an ultimatum to the Porte, demanding the right of intervention in conformity with the Treaty of Kainardji, threatening the invasion and occupation of the Danubian Principalities in default of immediate acquiescence.  Not having received the satisfaction he required, he ordered General Gortschakoff to cross the Pruth and to take possession of and hold the Principalities.  This was done in the month of July 1853.  In September the Turkish Commander-in-Chief on the Danube demanded an immediate evacuation of those territories, and, failing compliance, war was declared.  For some time the Russians, fearing the enmity of Austria, which had massed troops on the Wallachian frontier, remained on the defensive, but in October Omar Pasha assumed the aggressive, sending a small force across the Danube at Vidin, and it was thought that the straggle between the contending forces would take place in ’Lesser Wallachia.’  Omar Pasha, however, either intended this as a feint, or changed his plan, for he soon afterwards occupied strong positions on the Danube at Turtukai and Oltenitza, between Silistria and Rustchuk, and was there attacked by a Russian force, which he succeeded in repulsing.  No results followed this encounter; the Russians retreated towards Bucarest, and the Turks fell back across the Danube into Bulgaria.

In February 1854 the French and English Governments sent an ultimatum to Russia, requiring her to evacuate the Principalities, and in March they declared war against her.  In June Austria followed suit, so far as demanding the evacuation of Moldo-Wallachia, and received permission from the Porte to drive the Russians out of the Principalities, and occupy them with her troops.  She, however, contented herself during the continuance of the war with accumulating forces on her frontiers, and no doubt it was this threatening attitude which at length compelled Russia to evacuate them.  Meanwhile active hostilities were proceeding between Omar Pasha and Gortschakoff.  In the early part of 1854, the Russians having met with a reverse at Cetate, near Calafat, the Russian army was ordered to invade Turkey, and, having succeeded in crossing into the Dobrudscha at Galatz, Braila, and Ismail, it was deemed necessary to capture Silistria as a strategic post, in order to ensure the safety of the advancing army.  In May 1854 the Russians attacked that fortress unsuccessfully, and after they had attempted to storm it four times, the Turks (in June) assumed the offensive, and made a sally, during which one of the Russian generals was slain.  In the same month Nicholas, finding himself threatened by the Western allies in the Black Sea, and fearing to make an open enemy of Austria, whose forces were constantly increasing on her frontier, gave orders for raising the siege of Silistria, and subsequently for the entire withdrawal of his troops from the Principalities.  This was not, however, effected until July, nor before the Russians had sustained another defeat from the Turks at Giurgevo.