A Change in Plans: From Southern Expansion to Northern Campaign

In the early years of the Song Dynasty, Emperor Taizu (Zhao Kuangyin) had meticulously planned a strategy of “first pacify the south, then conquer the north” to reunify China. By 968, his forces had successfully subdued the Later Shu, a wealthy southern regime, filling the imperial coffers with its riches. Yet, just as the campaign against Southern Han seemed imminent, Zhao Kuangyin abruptly redirected his armies toward Northern Han—a move that defied his original blueprint.

Why this sudden pivot? Several factors converged to reshape his strategy:

1. Economic Windfall: The conquest of Later Shu had injected vast wealth into the Song treasury, enabling large-scale military operations.
2. Strategic Breathing Room: With rebellions in Shu quelled and southern territories stabilized, the Song military was free to act.
3. A Convenient Pretext: The death of Northern Han’s ruler, Liu Jun, nullified a prior non-aggression pact, giving Zhao Kuangyin moral and diplomatic cover.
4. A Personal Promise: The wistful remark of a surrendered Shu noblewoman—expressing her longing to return to her ancestral home in Taiyuan—struck a chord with the emperor, reinforcing his resolve.
5. An Unresolved Grudge: Northern Han had long been a thorn in Zhao Kuangyin’s side, a remnant of the Later Zhou’s unfinished campaigns and a symbol of his own rise to power.

The First Strike: Opportunity Meets Resistance

In late 968, Zhao Kuangyin launched his first major assault on Northern Han. The campaign began promisingly: Northern Han’s new ruler, Liu Jiyuan, faced internal strife, including the assassination of his predecessor. Yet, Liu Jiyuan proved a shrewd adversary. He swiftly secured support from the Khitan-led Liao Dynasty, whose cavalry arrived just as Song forces reached the outskirts of Taiyuan.

The siege faltered. Despite initial gains—including defections and the burning of Taiyuan’s gates—the Song army withdrew upon encountering Liao reinforcements. Northern Han’s resilience hinged on two pillars: the impregnability of Taiyuan’s fortifications and the unwavering support of the Khitans.

The Emperor’s Gambit: A Second Attempt

Undeterred, Zhao Kuangyin personally led a second expedition in 969. This time, he aimed to neutralize Liao interference. His strategists devised a two-pronged approach:

– Blocking Khitan Aid: General Han Chongyun ambushed Liao troops at Jiashan, while He Jiyun repelled another force at Yangqu.
– Besieging Taiyuan: Song armies encircled the city, constructing a network of fortifications and even diverting the Fen River to flood Taiyuan’s defenses.

Yet, fortune favored the defenders. A sudden storm thwarted a defection plot by Northern Han’s chancellor, Guo Wuwei. Floating debris miraculously plugged a breach in Taiyuan’s walls. Meanwhile, dysentery ravaged Song camps, and a renewed Khitan advance forced a retreat.

The Aftermath: Pyrrhic Victories and Lessons Learned

Though Taiyuan stood unconquered, the campaigns crippled Northern Han. Casualties mounted, and Song forces relocated thousands of households to the Central Plains, draining the kingdom’s manpower. Historians debate Zhao Kuangyin’s decision: Was abandoning the “south-first” doctrine a blunder?

Key takeaways emerge:

1. Geography as Destiny: Taiyuan’s natural and engineered defenses made it a fortress.
2. The Khitan Wildcard: Liao interventions repeatedly tipped the scales.
3. Logistical Limits: Flooding tactics were poorly executed, and disease sapped morale.
4. The Role of Chance: From weather to floating barricades, randomness shaped outcomes.

Legacy: A Foundation for Future Conquests

Zhao Kuangyin’s northern campaigns, though inconclusive, weakened Northern Han irreparably. By 979, his successor, Emperor Taizong, would finally annex the kingdom—a feat built on these earlier sacrifices. The episode underscores a timeless lesson: even the best-laid plans must adapt to the chaos of war.

For Zhao Kuangyin, Northern Han remained unfinished business—a reminder that reunification demanded not just strength, but patience. His turn southward to Southern Han would soon test whether flexibility could triumph where force had not.