 Russia is defeated on the southern front, Surovkin lines, Gerasimov's tactics collapse. The Zaporizhia front has been a buzz with news of Ukrainians breaking through Russia's first defensive line and chiseling away at a breach in the second. They're widening that breach at this stage to enable the flow of armored vehicles and logistics so they can exploit it. Michael Kaufman, defense analyst and senior fellow at Carnegie Endowment, told the Kiev Independent. The trend is in a positive direction, he added. Ukrainian generals are saying the first line was the hard part, the main, second line should be easier. The defense was counting on the Russians being able to retreat, said Viktor Givliuk, a retired Ukrainian colonel with the Think Tank Centre for Defence Strategies. But if there is no one left to retreat from the first line, who will defend the second? In many ways, these battle dividends are a function of the Ukrainian's courage and dedication, but it's Russia's baffling tactical choices that bear closer examination. Russian troops built hundreds of kilometres of competent multi-layered fortifications well suited for a defense in depth, yet spend months defending in front of the line with most available forces. Not just defending, but counter-attacking with infantry fighting vehicles and artillery pieces they can't afford to squander. The Russians have constructed a defense in depth in the south of Ukraine, but spent most of the counter-offensive not using it. Kaufman said, Kiev independent notes that in Zaporizia Oblast, there are three main layers running perpendicular to the Ukrainian attack, with smaller support layers enhancing them here and there. Defenses also run along major roads and encircle important towns like Robertine, which Ukraine took in early September. Each line has layers of its own, with trenches and strong points at the platoon, company and battalion levels, plus belts of minefields, tank obstacles, and other hindrances. Everyone correctly predicted that Ukraine would send its main attacks at Militopol and Burdiansk in an attempt to cut occupied Crimea from Russia and occupied parts of eastern Ukraine. Russian Army General Sergei Sorovkin ordered the lines to be built when he was in charge of the war effort, and they still bear his name. However, the general fell from grace after the warlord, Yevgeniy Prigoshin's short and unsuccessful rebellion. The command was handed back to Russian Army General Valery Garastimov, head of Russia's forces fighting against Ukraine. Under his watch, the Russian troops did not appear to use Sorovkin's defense in depth as originally intended. The Russians bunched up and held their ground, even trying to counterattack and recapture lost territory. Most attempts failed. Kivliuk said, Sorovkin wanted a classic positional defense, wearing down any advance over the course of several defense lines, while Garastimov prefers an active defense with regular counterattacks on the flanks. Kovman said, in this version of events, Garastimov may have been overconfident and overestimated what his force could achieve with active defense.