That accounts for the ease with which Ludendorf was able to throw 200,000 men into the frontal attack and still was able to send up 100,000 men to get into Rennenkampf's rear (see map No. 2). Rennenkampf's troops were kept engaged for seven days in repulsing Ludendorf's attacks upon their front, and he had no troops left with which to parry the attack on his rear. When the Germans invaded the Russian rear and were threatening to cut off the Russian main line of retreat, the Vershbolovo-Kovno Railroad, Rennenkampf was compelled to retreat so as not to be cut off. In fact, had Rennenkampf not retreated at that time, he would have committed the same act of treason that Marshal Bazaine was guilty of in 1870, when he, under similar circumstances, did not consent to escape from the steadily closing-up iron ring of Germans and was finally captured with his entire army. Rennenkampf gave orders to retreat only when the Germans were firing at the city of Gumbinnen and at his rear railway lines. This was not too soon by any means, but may have been rather a little late. [Illustration: Rennenkampf's troops are indicated between Welau and Ingenburg (white square). Opposite them is the German army (black square). Rennenkampf had 4 corps,--less than 160,000 men. He was attacked frontally also by 4 corps which engaged all his effectives. Meanwhile two German corps (the 17th and the 1st) that remained free began invading his rear (these corps are indicated in black). When these two corps approached Gumbinnen, they found themselves in a position to cut Rennenkampf off from his only road, the Insterburg-Kovno railway. Rennenkampf had no men to oppose these troops with, as all his units were fighting at the front line of Welau-Ingenburg. Rennenkampf was therefore compelled to retreat in order not to be cut off.] The 22nd Corps did not even succeed in getting near Rennenkampf, and was halted by the Germans fifty miles away from the field of battle. Rennenkampf had, therefore, not 200,000 men to Germany's 300,000, but only 160,000,--about one-half. The cause of the defeat of Rennenkampf was that that military operation had been calculated for the combined armies of Samsonov and Rennenkampf, and was a risky undertaking at that. When Rennenkampf was left alone, this operation was as a matter of course doomed to defeat, and it required the tenacity of Rennenkampf to have offered the obstinate resistance that he did in this battle. * * * * * * Transcriber's note: Obvious punctuation errors were corrected. Inconsistent hyphenation wss made consistent. Ludendorff consistently spelled Ludendorf but has not been corrected. p. 10: Apparent missing line in: "brought about the final defeat of the Germans in this [newline] sonov." pp. 45-6: Several misspellings of Rennenkampf corrected. p. 46: He was atacked frontally -> He was attacked frontally.