Caniza is a town in Lower Hungary, north of the River Drave, and just west of the Platen Sea, or Lake Balatin, as it is also called. Due north of Caniza a few miles, on a bend of the little River Raab (which empties into the Danube), and south of the town of Kerment, lay Smith's town of Olumpagh, which we are able to identify on a map of the period as Olimacum or Oberlymback. In this strong town the Turks had shut up the garrison under command of Governor Ebersbraught so closely that it was without intelligence or hope of succor.

In this strait, the ingenious John Smith, who was present in the reconnoitering army in the regiment of the Earl of Meldritch, came to the aid of Baron Kisell, the general of artillery, with a plan of communication with the besieged garrison. Fortunately Smith had made the acquaintance of Lord Ebersbraught at Gratza, in Styria, and had (he says) communicated to him a system of signaling a message by the use of torches. Smith seems to have elaborated this method of signals, and providentially explained it to Lord Ebersbraught, as if he had a presentiment of the latter's use of it. He divided the alphabet into two parts, from A to L and from M to Z. Letters were indicated and words spelled by the means of torches: "The first part, from A to L, is signified by showing and holding one linke so oft as there is letters from A to that letter you name; the other part, from M to Z, is mentioned by two lights in like manner. The end of a word is signifien by showing of three lights."