Konigsberg mobile force was to Cooperate from the Deime line. The ist and 8th Cav. Divs. grouped themselves in front of the right centre. The Landwehr and Ersatz units which had fought at Tannenberg were formed as a corps under von der Goltz (Goltz's Division, the new 3Sth Res. Div. formed of Unger's and Muhlmann's troops, and the 7oth Landwehr Bde.), with the mission of capturing Mlawa (which was accomplished on Sept. 4), defending the southern frontier in positions in advance of that point and of Willenberg, and prolonging the defence east- ward as the battle progressed.
The German forces, inclusive of one division of von der Goltz's corps, consisted, apart from cavalry, of about 16 divs.; those of the Russians, including troops which came into action from Grajevo, 14-16 divs. (II., III., IV., XX., XXII. Corps and 4-6 res. divs.). As usual, the Russian divs. were superior in infantry; the German, in artillery strength.
The battle opened generally on Sept. 7. On that day and the two following days the frontal attack of the Germans made only sloV progress, the Guard Res. Corps approaching AUenburg, the I. Res. Gerdanen, and the XX. Angerburg. One div. of the last named, originally kept back as army reserve to add weight to the decisive attack, had to be returned to the corps to enable it to progress in the Mauer See region. Farther to the S., the XVII. Corps, utilizing the gate of Lotzen, sought to debouch on Kruglanken, but the Russians, having intended to attack Lotzen, were in strength here, and the advance of this part of the German enveloping wing was arrested. Army headquarters now possessed no reserve, and to open the way for the XVII. Corps there was no alternative but to swing the greater part of the I. Corps sharply northward instead of northeastward. Thus delay was imposed on the striking wing of the attack; and when, on the night of Sept. 9-10, Rennenkampf decided to take down his line from right to left and retired eastward on Wirballen, Suwalki and Augustowo, it was already unlikely that the Germans would be able to place any important forces across the enemy's lines of retreat in time. Nevertheless, a great effort was made to achieve this result. The German I. Corps had advanced in three columns, the 2nd Div. by Nikolaiken on Arys, the ist Div. by Johannisburgon Bialla, with the 3rd Res. Div. on its right moving in the same direction. Von der Goltz, like Muhlmann in the Tannenberg operations, drew out his troops eastward as the 3rd Res. Div. advanced, keeping a closed group on that side and thinning the cordon at Mlawa and Willenberg. On Sept. 7 the German 2nd Div., after passing the defile of Nikolaiken, had become engaged at Gurra, N.E. of Lake Spirding, with a strong force of the Russian II. Corps that was ranged in a semicircle, facing W. and S. in the Arys defile. To enable the 2nd Div. to debouch, the ist Div., leaving the combat in the Bialla direction to the 3rd Res. Div., swung up to the N. to attack the S. face of the Russian semicircle at Arys. On Sept. 8 the Russian resistance was broken by the combined attack, and a brigade of the ist Cav. Div. attached to the I. Corps struck out northeast- ward to Klaussen. Meanwhile the 3rd Res. Div. had captured Bialla on Sept. 7th and pushed on to Drygallen on the Lyck road on Sept. 8, flankguarding towards Grajevo until the arrival of troops of von der Goltz's command enabled it to concentrate again.
On Sept. 9 the reunited I. Corps, master of the Arys defile, and joined by the two cav. divs. of the army, continued its north- ward movement so as to take the opponents of the XVII. Corps in rear. These stood on the line Mauer See-Goldapgar See- Soltmahner See-Gablick See, blocking the defiles between lake and lake. The pressure of the I. Corps from the S. and the XVII. Corps from the front, however, forced the evacuation of this position in the evening, especially as the two German cav. divs. were working out into the more open country towards Goldap. The XVII. Corps was thus released, and the enveloping move- ments of the German right wing began on Sept. 10. But the frontal attacks had made little impression, and Rennenkampf's XX., III. and IV. Corps were not effectively held in the Anger- burg-Gerdanen-Wehlau positions. On the night of Sept. o-io the order to take down the line was issued, and thereafter the
German frontal attack became a general pursuit, sometimes interrupted by stubborn rearguard fighting. By Sept. n the Guard Res. Corps had already fallen out of the scheme and was being grouped N.E. of Wehlau in reserve. The Konigsberg troops made for the E. side of Tilsit, to cut off the Russian force that had established itself there. But for the I. Res. Corps, the XI., the XX., and even for the XVII., the operation was a simple follow-up on the respective axes Insterburg-Pillkallen- Schirwindt; Nordenburg-Gumbinnen-Stalluponen; Angerburg- Darkehmen-Walterkehmen-Stalluponen; and Possessezn- Gawaiten-Wysztinice.
Ludendorff, while praising the achievement of the VIII. Army in covering 60 m. in four days against an enemy expert in rear- guard tactics, criticizes the pursuit in general as over-eager and lacking in coordination of effort, especially on Sept. 1 1 when the situation of the XL Corps led army headquarters to deflect the pursuit of the XVII. and I. Corps northward during some critical hours. Eventually, the XL, XX. and XVII. Corps all converged on Stalluponen and Kibarty; while farther N. the I. Res. Corps, moving in the last stages nearly E., came to a standstill about Wladyslawow. From Sept. 9 the German effort against Rennenkampf's left and rear was carried out entirely by the I. Corps and the cav. divs., while the 3rd Res. Div. and von der Goltz guarded the outer flank against intervention from Osowiec and Augustowo or Suwalki. On this wing the record of Sept. 10-3 is one of true manoeuvre.
According to the army orders for Sept. 10, the role of the I. Corps was to flankguard the XVII. in its attempt to strike in on Rennenkampf's rear E. of Angerburg, no general retreat of the Russians from Angerburg-Wehlau having yet begun. Accord- ingly, the two divs. of Francois's corps were directed on the line Lissen-Pillacken ; while the 3rd. Res. Div., which had taken the Lyck road on Sept. 9 instead of swinging up with the others, was to drive in its Lyck opponents and then take the direction Marggrabowa-Filipowo. The ist and 8th Cav. Divs., which had reached Goldap over night, were to make for Gumbinnen. But in the evening of Sept. 10 it became clear at the German head- quarters that the Russian retirement was in progress, and the positions of the German right wing just mentioned became the starting-points of an attempt to reach the enemy's lines of retreat.
On Sept. ii the I. Corps was to advance with its right pushed forward, to Goldap, and thence S. of the Rominten Heath on Mariampol; the XVII. Corps along the N. side of Rominten Heath, on Wistyniec; the cav. divs. in advance against the Insterburg-Kovno routes. But at midday both corps were ordered to swerve inwards owing to difficulties in which the XL Corps was supposed to have become involved near Darkehmen. As the right of the I. Corps was echeloned forward, this move in effect crowded out the XVII. Corps, as well as diverting the I. Von Francois, however, was unwilling to give up the attempted encirclement, and only wheeled up one of his divs. from Goldap on Gawaiten, while the other pushed N.E. along the N. side of Rominten Heath to Tollmingkehmen the route originally assigned to the XVII. Corps. Later in the day, the alarm at the XI. Corps' front having proved to be baseless, the I. Corps was again directed N.E. towards Pilluponen and Wilkowiszki. But the amplitude of the army wheel had been diminished by a corps front. Wilkowiszki, instead of being the objective of the XVII. Corps, had become that of the I. Only the cav. divs. were left to pursue the advance S. of Rominten Heath on Mariampol. Meantime the 3rd Res. Div. moved from Lyck on Marggrabowa, von der Goltz's Landwehr div. following on as a right echelon against interventions from the S.E. or E.
During Sept. 12 the two parts of the I. Corps had heavy fighting at Gawaiten, Tollmingkehmen and Baubeln with the advanced and flank guards of various Russian columns which were retreating through the country S. of Darkehmen and Stalluponen. All these were checked and deflected northward, but none was cut off, though by evening the right of the Germans had extended up to Pilluponen. Von Franfois, under cover of his ist Div.'s positions at Tollmingkehmen-Pilluponen, passed the whole 2nd Div. through the Rominten Heath (having only
