Believing the northern approaches to the city too well defended, especially due to the presence of a large star fort and because Sevastopol was on the south side of the inlet from the sea that made the harbour, Sir John Burgoyne, the engineer advisor, recommended that the allies attack Sevastopol from the south. This was agreed by the joint commanders, Raglan and St Arnaud.:426 On 25 September the whole army marched southeast and encircled the city to the south. This let them set up a new supply center in a number of protected inlets on the south coast. The Russians retreated into the city.
When did the army march to the southeast?  
25 September

Tucson (/ˈtuːsɒn/ /tuːˈsɒn/) is a city and the county seat of Pima County, Arizona, United States, and home to the University of Arizona. The 2010 United States Census put the population at 520,116, while the 2013 estimated population of the entire Tucson metropolitan statistical area (MSA) was 996,544. The Tucson MSA forms part of the larger Tucson-Nogales combined statistical area (CSA), with a total population of 980,263 as of the 2010 Census. Tucson is the second-largest populated city in Arizona behind Phoenix, both of which anchor the Arizona Sun Corridor. The city is  located 108 miles (174 km) southeast of Phoenix and 60 mi (97 km) north of the U.S.-Mexico border. Tucson is the 33rd largest city and the 59th largest metropolitan area in the United States. Roughly 150 Tucson companies are involved in the design and manufacture of optics and optoelectronics systems, earning Tucson the nickname Optics Valley.
What industry-based nickname does Tucson have?
Optics Valley

About 98% of Antarctica is covered by the Antarctic ice sheet, a sheet of ice averaging at least 1.6 km (1.0 mi) thick. The continent has about 90% of the world's ice (and thereby about 70% of the world's fresh water). If all of this ice were melted, sea levels would rise about 60 m (200 ft). In most of the interior of the continent, precipitation is very low, down to 20 mm (0.8 in) per year; in a few "blue ice" areas precipitation is lower than mass loss by sublimation and so the local mass balance is negative. In the dry valleys, the same effect occurs over a rock base, leading to a desiccated landscape.
How thick is the ice that covers Antarctica?
1.6 km