Germany was not formed until after Napoleon had been defeated and the Napoleonic Wars were over. As the soldiers are still fighting Napoleon, they would not refer to Germany as Germany,
The British soldiers say they want to retreat to Germany and then to the coast. In actuality they had just fought a battle with the French while the Prussians to the east had had just fought the French and lost. If they retreated toward Germany, they would need to retreat through a victorious French Army to get to Germany.
A more feasible retreat would have been west away from Germany and toward the coast which would be closer geographically.
A more feasible retreat would have been west away from Germany and toward the coast which would be closer geographically.