Short answers, pulled from the story.
The Battle of Narva lasted from the 2nd of February to the 10th of August 1944. It consisted of two major phases: the Battle for Narva Bridgehead from February to July, and the Battle of Tannenberg Line in July and August.
Control of the 45-kilometre-wide Narva Isthmus would have given the Soviet Union a clear route to Tallinn, access to the Baltic Sea for the trapped Baltic Fleet, and bases for air and amphibious attacks against Finland and an invasion corridor into East Prussia. Germany needed to hold the adjacent Kohtla-Järve oil shale deposits and keep the Soviet Baltic Fleet bottled up.
A total of 70,000 Estonian troops were under German arms in 1944, including 38,000 men raised by the mobilisation call of acting head of state Jüri Uluots, organised into seven border guard regiments and the Estonian Division, plus voluntary Estonians in the Finnish army as Finnish Infantry Regiment 200 and conscripts within the Waffen SS.
The German Army Detachment "Narwa" held the Tannenberg Defence Line in the Sinimäed Hills against repeated Soviet attacks. Of the 136,830 Soviet troops who launched the offensive on the 25th of July 1944, only a few thousand remained fit for combat by the 1st of August. Leningrad Front commander Leonid Govorov terminated the offensive on the 10th of August.
The prolonged German defence denied the Soviet Union Estonian bases needed for attacks against Finland, helping Finland avoid Soviet occupation and negotiate the Moscow Armistice on its own terms. Finnish Chief of Defence Carl Gustaf Emil Mannerheim had warned that a German retreat from Estonia would force Finland to accept peace on any Soviet terms.
On the 18th of September 1944, acting head of state Jüri Uluots appointed a government under Otto Tief, which briefly raised the Estonian flag above Pikk Hermann tower in Tallinn before Soviet troops removed it four days later. The Estonian Government in Exile maintained legal continuity of the Estonian state until 1992, when it handed its credentials to incoming President Lennart Meri.