Hundreds of emergency personnel -- backed by helicopters, army vehicles and police water canon -- have been fighting the flames and evacuated four nearby villages with a total of over 1,000 residents in the northeastern Mecklenburg-Western Pomerania state.
The acrid smell from the blaze, the largest recorded in the ex-communist northeastern state, has drifted as far as Berlin, 200 kilometres away, as much of Europe swelters in blistering summer temperatures.
SEE ALSO: Hundreds evacuated as wildfire rages through eastern Germany
The German army on Tuesday sent in armoured vehicles to clear pathways of dangerous unexploded ordnance (UXO) so that fire engines can enter the burning region that measured some 600 hectares (1,400 acres).
A helicopter drops water over the small community of Alt Jabel. Photo: DPA
The former military training ground near the town of Lübtheen is littered with bombs, grenades and bullets from the Nazi era's Wehrmacht, the former Soviet army, and from reunited Germany's Bundeswehr.
Tests in the past had unearthed more than 45 tonnes of UXO per hectare, state environment minister Till Backhaus told local newspaper the Ostsee
Zeitung, adding: "I pray to God that he sends us rain, as quickly as possible."
The blaze has become the "largest in the history of Meckenburg-Western Pomerania," he said on Monday.
Forest fires have become more prevalent in recent years in Germany. Some of the blazes have proved particularly difficult to extinguish, as the ground sometimes contains left-over ammunition from World War II, and the fire causes old hand grenades and cartridges to detonate.
SEE ALSO: Hundreds evacuated near Berlin as forest fire threatens villages