First Battle of the Masurian Lakes

Background

Tannenberg had destroyed the centre of Samsonov's Second Army by 30 August 1914, but Rennenkampf's First Army was still in East Prussia, untouched. On 31 August the German Supreme Command gave the Eighth Army its next task: clear East Prussia of Rennenkampf's army. Hindenburg and Ludendorff read that as more than pushing him over the border. They meant to beat him badly enough to leave the army free for whatever came next, very likely a move towards Warsaw to help the hard-pressed Austro-Hungarians. Two corps had already come from the Western Front, the Guard Reserve Corps and XI Corps, together with the 8th Cavalry Division. They began unloading behind the front on 2 September and made the army nearly half as strong again.

Rennenkampf had fallen back after Tannenberg into the country north-west of the Masurian Lakes. Zhilinsky, commanding the North-Western Front, ordered him on 31 August to defend it stubbornly. His chief of staff, Mileant, proposed falling back to the line Insterburg–Goldap, from where the army could threaten any German advance through the lakes from the north. Rennenkampf refused, fearing the effect of a further retreat on morale. His line ran from the Kurisches Haff along the Deime and through Allenburg and Gerdauen to the Mauer-See west of Angerburg. His right rested on the sea and his left on the lakes. To the south a new Tenth Army was assembling around Lyck and Grajewo to close the gap left by Samsonov's army.

The northern flank could not be turned without crossing the Pregel. Hindenburg therefore chose the southern one, sending a strong wing through the lake passes at Lötzen and Nikolaiken and round the southern end of the lakes, behind Rennenkampf's line.

The armies

By early September the Eighth Army had 13 active and reserve infantry divisions, 5½ divisions' worth of Landwehr and replacement troops and two cavalry divisions. In all it had 229 battalions, 119 squadrons and 1,194 guns. Hindenburg split it. About 8½ divisions went against the fortified front north of the lakes: Scholtz's XX Corps, Plüskow's XI Corps, Below's I Reserve Corps and Gallwitz's Guard Reserve Corps. The outflanking wing had five divisions: François's I Corps, Morgen's 3rd Reserve Division and Mackensen's XVII Corps, with the 1st and 8th Cavalry Divisions behind them. A Landwehr division under von der Goltz covered their rear against the Tenth Army.

Rennenkampf had 16½ infantry divisions, 8½ of them active and the rest reserve, and 5½ cavalry divisions. Only 14 infantry divisions were at the front. North of the lakes the Germans reckoned on at least 176 Russian battalions against at most 152 of their own. Most of his reserves stood behind the northern flank, where he expected a landing from the Haff or the sea. On the southern flank, east of the lakes, there was little more than the 43rd Division.

The German staff respected Russian field fortification after Manchuria and had no experience of attacking entrenched lines. One lesson of Tannenberg had been learnt: the Russians now enciphered their wireless traffic. The Germans tried a deception instead. On 7 September Königsberg broadcast an uncoded message about the Guard Corps and V Corps unloading near Labiau, and the Russians picked it up.

The battle

Through the lake passes, 5–8 September. On 5–6 September François's leading troops met Russians near Johannisburg. On 7 September, after marching 100 km in three days along the frontier, Morgen's 3rd Reserve Division struck the flank of the Finnish rifle brigades of the Russian XXII Corps, the vanguard of the Tenth Army, at Bialla. It took 400 prisoners and eight guns. Early on 8 September François's 1st Division cleared Arys and took 1,000 prisoners. Mackensen's XVII Corps came out of Lötzen and closed up to the fortified Russian line between the Goldapgar-See and the Mauer-See. North of the lakes the frontal corps advanced cautiously towards Gerdauen and Allenburg. Hindenburg moved his headquarters to Rössel to direct the battle.

The southern wing attacks, 9 September. This is the CDB90 engagement (Masurian Lakes, 9–14 September). XVII Corps had a hard day. Its 35th Division fought for Kruglanken against well-hidden batteries and repeated counter-attacks, and took the position only at dusk. Further north, Colonel Bressler turned Infantry Regiment 129 on his own initiative against a weak point at Possessern. With the 71st Brigade he stormed the village with the bayonet in the afternoon, taking 1,000 prisoners and two batteries. The Russian line was broken. François pushed I Corps north on both sides of the Widminner See, deep into the Russian flank. North of the lakes the German attacks made no headway: XX Corps halted, and the Guard Reserve Corps, facing unbroken Russian artillery, was stopped before Allenburg after heavy losses. Behind the front, Morgen fought the XXII Corps west of Lyck until nightfall. Rennenkampf had sent the XX Corps and two reserve divisions south towards Darkehmen and Goldap. That afternoon he nevertheless ordered the front north of the lakes to retreat.

The Russians slip away, 10 September. At first light the XI Corps and I Reserve Corps found the trenches around Gerdauen empty and the town burning. Only an air report late in the morning confirmed that the whole Russian army was retreating. The 8th Cavalry Division took Goldap and 600 prisoners. The 2nd Division took 32 guns near Kutten. A call for help on Morgen's behalf cost the Germans the 1st Cavalry Division. It was sent south just when it was meant to ride into the Russian rear, and Morgen's report that he had already beaten the XXII Corps arrived soon after.

The pursuit, 11–14 September. On 11 September Russian counter-attacks at Goldap and south of Darkehmen held up the outflanking wing. A false report that XI Corps was under heavy attack made Hindenburg turn I and XVII Corps north. By evening four German corps nearly ringed a Russian mass of about six divisions around Darkehmen, but no headquarters knew it, and the Russians got away north-east in the night. On 12 September François disputed his orders and the Russians escaped through a gap at Tollmingkehmen. XVII Corps took 3,000 prisoners there. Königsberg troops occupied Tilsit and the next day captured an isolated regiment, with 4,000 prisoners and twelve guns. On 13 September rain and mud slowed the cavalry, and XI Corps took 2,000 prisoners in street fighting at Stallupönen. By the evening of 14 September the Germans were at Wilkowischki and Schirwindt, East Prussia was clear, and the pursuit ended.

Aftermath

The Reichsarchiv counted 45,000 prisoners and 150 guns. It cites a Russian figure of 100,000 total losses (70,000 killed and wounded, 30,000 prisoners), against about 9,000 Germans. Other estimates run from about 60,000 to 125,000 Russian losses. Rennenkampf's army got back over the frontier with most of its men, but in disorder, mixed up and badly shaken. It had to fall back behind the Niemen to reorganise. Counting Gumbinnen and Tannenberg as well, the Reichsarchiv puts German losses in East Prussia at about 37,000 and Russian at about 250,000, 145,000 of them prisoners.

The battle won back the province but missed its larger aim. Rennenkampf retreated before the trap could close, and the Reichsarchiv blamed the gap on his early withdrawal, the diverted cavalry, the false alarm of 11 September and François's independence on the 12th. Zhilinsky was dismissed on 11 September and replaced by Ruzsky. Within days the Germans were forming the Ninth Army for Silesia and Poland. The Russians struck back on the Niemen on 25–28 September and regained much of the ground.

The Reichsarchiv itself complained that Tannenberg's vast prisoner haul had overshadowed this battle, despite the boldness of its plan.

Wargaming it

This is a corps-and-division battle over a front of roughly 150 km. It suits operational games with divisions or brigades as units, half-day or daily turns and hexes of 3–5 km. The board needs the Haff and Deime in the north-west, the lakes in the middle and the Lyck–Grajewo frontier in the south-east, with Insterburg, Darkehmen and Goldap as the prizes behind the Russian line.

The lakes are the system. A few passes at Lötzen, Nikolaiken and Arys, and the fortified isthmuses at Kruglanken and Possessern, decide how fast the German left hook can come round. Every day spent there gives Rennenkampf a day to read the threat. The German player must split the army against a numerically stronger enemy and accept that his frontal corps may face a counter-attack on their own for several days.

The Russian player's best weapon is the retreat. A rule that lets him break contact at night, as Rennenkampf did on 9–10 September, makes the game a race rather than a slugging match. Hidden deployment and limited German air reconnaissance matter more than firepower.

What-ifs: Rennenkampf adopts Mileant's plan and stands back on the Insterburg–Goldap line; he throws his northern reserves at the thin German left, as the German staff feared; the Tenth Army attacks the German rear in concert instead of in fits; the 1st Cavalry Division is not sent south on 10 September.

Maps and pictures

Pictures from the time

Photographs by the armies' photographers and the press, and drawings made at the time: free-to-use pictures from the battle's category on Wikimedia Commons. Each opens its file page there, with the full caption and source.