What battle saw the first use of tanks? what country did german first declare war on

The heavily shelled terrain was impassable to conventional vehicles, and only highly mobile tanks such as the Renault FTs and Mark IV performed reasonably well. There were problems that caused considerable attrition rates during combat deployment and transit. The first tanks were mechanically unreliable. Whilst the Allies manufactured several thousand tanks during the war, Germany deployed only 18 of its own. The Germans, on the other hand, began development only in response to the appearance of Allied tanks on the battlefield. The French fielded their first tanks in April 1917 and ultimately produced far more tanks than all other countries combined. The term was chosen when it became known that the factory workers at William Foster referred to the first prototype as 'the tank' because of its resemblance to a steel water tank. Although initially termed 'Landships' by the Landship Committee, production vehicles were named 'tanks', to preserve secrecy. The prototype of a new design that became the Mark I tank was demonstrated to the British Army on 2 February 1916. In Great Britain, an initial vehicle, nicknamed Little Willie, was constructed at William Foster & Co., during August and September 1915. Research took place in both Great Britain and France, with Germany only belatedly following the Allies' lead. Although vehicles that incorporated the basic principles of the tank (armour, firepower, and all-terrain mobility) had been projected in the decade or so before the War, it was the alarmingly heavy casualties of the start of its trench warfare that stimulated development. The development of tanks in World War I was a response to the stalemate that developed on the Western Front. A British Mark V* tank- carries an unditching beam on the roof that could be attached to the tracks and used to free itself from muddy trenches and shell craters A British tank destroyed by the Germans on the Western Front, 1917

What battle saw the first use of tanks? what country did german first declare war on