The collapse of the Eastern Roman Empire was primarily caused by external factors like foreign invasions, not internal decay.
The prolonged Roman-Persian war in the early 7th century critically weakened both empires, creating the power vacuum that enabled the Arab conquests.
Modern U.S. foreign policy exhibits a significant disconnect between its idealistic public rhetoric and its actual geopolitical actions.
The Eastern Roman Empire's survival and decline were repeatedly shaped by multi-front wars and the ability to form strategic alliances with external powers like the Turks and Bulgars.
Major demographic and ecological shifts, such as the Seljuk migration transforming agricultural land into pasturage, were significant catalysts in historical change.
602-628
Kaldellis analyzes the devastating Roman-Persian war, highlighting how a Roman civil war (608-610) gave Persia a massive advantage, leading to its conquest of Syria, Palestine, and Egypt before Emperor Heraclius achieved a final victory with Turkish allies.
c. 630s - 718
He discusses the period of Arab conquests, arguing they succeeded because the Roman and Persian empires were exhausted from their prior war and because the attacks came from the unexpected direction of Arabia. He notes the two failed Arab sieges of Constantinople as crucial for Roman survival.
c. 955 onwards
Kaldellis points to a period of military resurgence for the Eastern Roman Empire, when it went on the offensive and conquered territories in Cilicia, northern Syria, Cyprus, the Caucasus, and Bulgaria.
11th Century
He describes a critical turning point where the empire faced a simultaneous three-front attack from Seljuk Turks, Pechenegs, and Normans, which coincided with a major ecological and demographic shift in Asia Minor caused by the Seljuks.
1300-1350
Kaldellis identifies this period as the beginning of the empire's final, irreversible decline, triggered by the loss of Asia Minor to the Turks, a series of civil wars, and Serbian expansion.
Early 15th Century
He notes that Timur's defeat of the Ottoman Turks delayed the final conquest of Constantinople by approximately 50 years, forcing the Turks into a period of rebuilding.
▶External Pressure as the Primary Driver of Imperial CollapseJun 2026
Kaldellis consistently argues that the decline and fall of the Eastern Roman Empire were not due to internal rot but were a direct result of overwhelming external military pressures. He points to the simultaneous three-front war in the 11th century and the final blow from foreign invasions as key evidence for his thesis.
This perspective challenges deterministic 'rise and fall' models, suggesting that analysts should prioritize external geopolitical threats and military capabilities over internal social metrics when assessing state stability.
▶The Geopolitical Domino Effect of Prolonged WarfareJun 2026
He emphasizes how long, attritional wars create power vacuums that enable the rise of new powers. The decades-long Roman-Persian conflict (602-628) exhausted both empires, leaving them vulnerable to the strategically unexpected Arab invasions from the south.
Investors and analysts should monitor not just the primary combatants in a protracted conflict but also the opportunistic third parties on the periphery, as they are often the conflict's ultimate beneficiaries.
▶The Rhetoric vs. Reality of Foreign PolicyJun 2026
Kaldellis draws parallels between historical empires and modern states, specifically critiquing the gap between the stated ideals and actual motivations of U.S. foreign policy. He cites the 'feminist war' justification for invading Afghanistan as an example of implausible rhetoric used to mask geopolitical objectives.
This highlights the importance of deconstructing official state narratives to identify underlying strategic interests, a critical skill for geopolitical risk analysis.
▶Strategic Alliances and Shifting FrontsJun 2026
Kaldellis details how the Eastern Roman Empire navigated existential threats through strategic, often cross-cultural, alliances. Examples include Emperor Heraclius allying with Central Asian Turks against Persia and Emperor Leo III allying with the Bulgars against the Arabs, demonstrating diplomatic flexibility as a key survival tool.
The ability of a state to form pragmatic alliances, even with historical adversaries, is a key indicator of its resilience and adaptability in a complex security environment.