Even from the beginning of the year 1584 Parma had been from time to time threatening Antwerp.  The victim instinctively felt that its enemy was poising and hovering over head, although he still delayed to strike.  Early in the summer Sainte Aldegonde, Recorder Martini, and other official personages, were at Delft, upon the occasion of the christening ceremonies of Frederic Henry, youngest child of Orange.  The Prince, at that moment, was aware of the plans of Parma, and held a long conversation with his friends upon the measures which he desired to see immediately undertaken.  Unmindful of his usual hospitality, he insisted that these gentlemen should immediately leave for Antwerp.  Alexander Farnese, he assured them, had taken the firm determination to possess himself of that place, without further delay.  He had privately signified his purpose of laying the axe at once to the root of the tree, believing that with the fall of the commercial capital the infant confederacy of the United States would fall likewise.  In order to accomplish this object, he would forthwith attempt to make himself master of the banks of the Scheldt, and would even throw a bridge across the stream, if his plans were not instantly circumvented.

William of Orange then briefly indicated his plan; adding that he had no fears for the result; and assuring his friends, who expressed much anxiety on the subject, that if Parma really did attempt the siege of Antwerp it should be his ruin.  The plan was perfectly simple.  The city stood upon a river.  It was practicable, although extremely hazardous, for the enemy to bridge that river, and by so doing ultimately to reduce the place.  But the ocean could not be bridged; and it was quite possible to convert Antwerp, for a season, into an ocean-port.  Standing alone upon an island, with the sea flowing around it, and with full and free marine communication with Zeeland and Holland, it might safely bid defiance to the land-forces, even of so great a commander as Parma.  To the furtherance of this great measure of defence, it was necessary to destroy certain bulwarks, the chief of (10th June, 1584) which was called the Blaw-garen Dyke; and Sainte Aldegonde was therefore requested to return to the city, in order to cause this task to be executed without delay.

Nothing could be more judicious than this advice.  The low lands along the Scheldt were protected against marine encroachments, and the river itself was confined to its bed, by a magnificent system of dykes, which extended along its edge towards the ocean, in parallel lines.  Other barriers of a similar nature ran in oblique directions, through the wide open pasture lands, which they maintained in green fertility, against the ever-threatening sea.  The Blaw-garen, to which the prince mainly alluded, was connected with the great dyke upon the right bank of the Scheldt.  Between this and the city, another bulwark called the Kowenstyn Dyke, crossed the country at right angles to the river, and joined the other two at a point, not very far from Lillo, where the States had a strong fortress.