He picked up the first piece and held it over the map’s eastern section.

Volga Bulgaria. The Bulgar state had been there for centuries, a Turkic-Muslim trading civilization built on the middle Volga’s commerce. Their capital at Bulgar city, on the river’s left bank south of the Kama confluence. Secondary cities at Suvar, at Bilyar.

A professional standing force somewhere between ten and fifteen thousand men, with perhaps thirty thousand total they could put in the field if they raised their full levy. They were capable defenders on prepared positions, and had no cavalry force that could engage on open ground without being cut apart.

They had beaten a Mongol raiding force in more than a decade ago. They probably considered it as evidence they can resist further.

It was not evidence of anything that would help them.

The Jochid army alone was sufficient. He did not need to wait for the other tumens. He returned west from Karakorum, he struck immediately, and Bulgar city fell before the Toluid and Ogedeid armies had even finished mobilization.

The other tumens would take months to march from their various starting positions. By the time they arrived at the Volga, the base would already be there.

The army would do what armies did when they reached a city that had fought them. He had no plans to interfere with the general course of it. It would cost cohesion before the Rus campaign even opened, and the Rus campaign was what mattered in the early stage.

Batu would have Khulgen or a designated officer move through ahead of the plundering and extract craftsmen, administrators, anyone with skills his founding city needed before the opportunity closed.

The city on the Volga river required population. The Bulgars were the nearest available source of the kind of urban people. That was the pragmatic move, and it was the extent of it.

He set the first piece on Bulgar city’s position and looked at the map.

He reached into the pouch and took out the next two pieces.

The Toluid army would approach from the southeast. Mongke’s three tumens, experienced commanders, riders who had spent their lives on steppe ground and would handle the transition into the forest zone better than he had reason to expect from a force that had never fought west of the Ural.

They would march through the autumn of 1236 and reach the Volga mobilization area through the early winter.

He set the Toluid piece southeast of the Jochid position, at the direction of approach.

The Ogedeid tumens were similar in size. Less experienced leadership in this specific terrain, but capable enough for the purpose they would serve.

They came from a different direction, traveling their own route through the northern steppe.

He set their piece alongside the Toluid, the two of them flanking the Jochid position.

He looked at the three pieces together.

The entire mobilized force would be ready by the start of winter 1237. In calendar terms that was over a year and a half from now.

The Bulgar campaign came first, then the mobilization, then the entire army moved together.

Subutai had been thinking about the western campaign since before the kurultai. His thinking and Batu’s had arrived at the same answer through different routes, which was its own confirmation.

Now he looked at the territory north and west of where the Jochid piece sat.

The Rus principalities. A dozen of them, fragmented, competing with each other for land and commerce and precedence. They had no common military command. They had no tradition of coordinated defense.

Their princes called each other to war as often as they called each other to alliance, and the difference between those two calls was sometimes a matter of weeks.

In the other life, that fragmentation had created a campaign that destroyed the Rus principalities one at a time, each one watching the others fall without sending enough help to stop it.

Nobody had made that happen from the Mongolian side. It had happened because the Rus princes were politically dysfunctional and the Mongol force moved faster than their communications.

He could make it happen even further.

He looked at the map’s northern section. The road from Ryazan northwest toward Vladimir-Suzdal went through open ground before it reached the forest zone.

A force positioned on that road before Ryazan’s envoys reached Vladimir would be visible to any relief army before it had time to organize.

He picked up the Toluid piece from its stand-by position and moved it.

He set it northeast of Ryazan’s location on the felt, on the Vladimir-Suzdal route. Mongke’s three tumens, in position before the Jochid army reached Ryazan’s walls.

A Vladimir prince in that situation would not would not march south.

The reason was simple, if he marched south and Ryazan still fell, he had nothing to garrison his own city when the Mongol army turned to it.

He would wait. They always waited.

He moved the Ogedeid piece south.

Chernigov was the second principality with any capacity to send relief. The Ogedeid tumens covered the southern wing.

The logic applied. A Chernigov prince with Mongol forces on his backyard would look at his own walls, not at Ryazan.

The Jochid main body moved from the Volga directly east of Ryazan. Through the Mordvinian transition zone between the steppe and the forest, across the frozen Oka, to the confluence where the Pronya met it and where Ryazan sat on the high bank above the crossing.

The Rus princes understood defense as staying inside walls and waiting for the attacker to exhaust himself in the cold.

That assumption had been tested against different armies. It had not been tested against this one.

He picked up the Jochid piece from Bulgar city and set it on Ryazan’s position.

The three pieces sat on the map. The Jochid force at Ryazan, the Toluid force blocking Vladimir, the Ogedeid force covering Chernigov.

A city surrounded not by walls of riders but by the absence of anywhere its princes could send for help that would arrive in time.

He held the lamp close and looked at the map for a moment.

The board showed the opening.

The first piece was down.

He set the lamp back and looked at the map for a longer time.