It was on impregnable ground , and was guarded Patrolling well .

The siege of Golconda lasted 8 months and on various occasions it had pushed Body_movement the massive Mughal army to its limits , in fact the Golconda Fort was probably the most impregnable fort in the Indian subcontinent .

The Italian Chief of the general staff general , Luigi Cadorna , had ordered Arranging the construction of fortified defenses around the Monte Grappa summit in order to make the mountain range an impregnable fortress .

At that time , the Portuguese had transformed Change Malacca into an impregnable fortress ( the `` Fortaleza de Malaca '' ) , controlling Control access to the sea lanes of the Straits of Malacca and the spice trade there .