coast of Morocco, east to Tunis. This portion of the border is easily defensible at the small number of passes through the two north–south lines of the mountains. In the south a lower range of mountains limit the approaches to a narrow gap, facing Libya to the east, between the Matmata Hills and the coast. The French had earlier constructed a wide and deep series of defensive works known as the Mareth Line along the plain, to defend against an Italian invasion from Libya. Only in the north was the terrain favourable to attack; here the Atlas Mountains stopped near the eastern coast, leaving a large area on the north-west coast unprotected. Defensive lines in the north could deal with approaching forces, while the Mareth Line made the south secure. In between, there were only a few easily defended passes through the Atlas Mountains. Tunisia has two big deep water ports at Tunis and Bizerte, only a few hundred miles from Italian supply bases in Sicily. Ships could deliver supplies at night, safe from RAF patrols and return the next night, while Libya was a full-day trip, making supply operations vulnerable to daylight air attacks. In Hitler's view, Tunisia could be held indefinitely, upsetting Allied plans in Europe. Run for Tunis By 10 November, French opposition to the Torch landings had ceased, creating a military vacuum in Tunisia. The First Army (Lieutenant-General Kenneth Anderson) was immediately ordered to send the 36th Infantry Brigade Group, which had been the floating reserve for the Algiers landing, eastward by sea to occupy the Algerian ports of Bougie, Philippeville, and Bône and the airfield at Djedjelli, preliminary to advancing into Tunisia. The Combined Chiefs of Staff had decided that with the forces available, Torch would not include landings close to Tunisia. Anderson needed to get his limited force east quickly, before the Axis could reinforce Tunisia, but the Allies had only two brigade groups and some additional armour and artillery for the attack. The French governor in Tunisia, Admiral Esteva, was afraid to support the Allies or oppose the Axis. He did not close airfields to either side; the Germans moved first and by 9 November, there were reports of 40 German aircraft arriving at Tunis and by 10 November, aerial reconnaissance reported 100 aircraft. Two days later, an airlift began that carried over 15,000 men and of supplies and ships brought 176 tanks,