近卫军是罗马帝国初期建立的一支特殊武装，在前期罗马帝国历史具有举足轻重的影响，是左右元首政治的一股特殊力量。对罗马近卫军的研究，能够开拓和深化罗马史的研究，使我们能更清晰地认识罗马帝国的政治和社会。

本文探讨了关于罗马近卫军的四个问题，即近卫军为何能出现，近卫军为何能崛起，近卫军如何影响元首政治，近卫军对罗马历史产生了什么样的影响。

本文从近卫军创立之初，以从共和走向帝国背景下的朱里亚-克劳狄王朝历史为中心，对近卫军与元首政治的关系及演变进行探讨。第一，建立帝制的时代需要带来了近卫军，但奥古斯都创立的元首制缺陷埋下了近卫军崛起的隐患。第二，在朱里亚-克劳狄王朝的四位元首统治时期，提比略使近卫军进驻罗马城，近卫军力量集中于首都，近卫军长官权势地位的大大提高，对近卫军大加赏赐等因素加速了近卫军的崛起。第三，提比略之后的三位元首缺乏能力驾驭近卫军，对近卫军的依赖程度日渐加深，使得近卫军的负面影响日渐严重。第四，卡里古拉死于近卫军之手已然反映双方势力的失衡，克劳狄的继位是近卫军干涉元首继承的一次成功尝试，标志着近卫军对元首政治介入的加深。尼禄统治期间亦未能解决近卫军问题，尼禄之死成为朱里亚-克劳狄王朝终结的标志，近卫军在尼禄之后的公元68-69年内战期间成为左右罗马政局的关键力量，使得罗马元首政治运行日益畸形，给之后的弗拉维王朝提出了严重的挑战。

总体而言，朱里亚-克劳狄时期近卫军的崛起和发展为后续的百年帝国史埋下了历史的“因”，这一时期近卫军产生的诸多负面影响将在时代的层层累积下不断加深，成为推动罗马帝国衰亡的一个重要因素。

The Praetorian Guard was a special military unit established in the early Roman Empire, playing a pivotal role in the history of the early Empire and acting as a unique force influencing the politics of the principate. Research into the Praetorian Guard can expand and deepen our understanding of Roman history, providing clearer insights into the political and social dynamics of the Roman Empire.

This paper discusses four key issues concerning the Praetorian Guard: the reasons for its emergence, its rise to power, its impact on the politics of the principate, and its overall influence on Roman history.

Centered on the historical context of the transition from the Republic to the Empire during the Julio-Claudian dynasty, the paper examines the relationship and evolution between the Praetorian Guard and the politics of the principate. Firstly, the era of establishing the Empire necessitated the creation of the Praetorian Guard, but the flaws in the principate system founded by Augustus sowed the seeds for the Guard's eventual rise. Secondly, during the reign of the four emperors of the Julio-Claudian dynasty, Tiberius stationed the Praetorian Guard in Rome, concentrating their power in the capital and significantly elevating the status and influence of the Guard's commanders, with factors such as generous rewards accelerating their ascent. Thirdly, the three emperors following Tiberius lacked the ability to control the Guard, increasingly depending on them, which led to the Guard's growing negative impact. Fourthly, Caligula's assassination by the Praetorian Guard reflected an imbalance of power, and Claudius's succession was a successful attempt by the Guard to interfere in the imperial succession, marking a deepening involvement of the Guard in principate politics. Nero's reign failed to address the issues with the Guard, and his death marked the end of the Julio-Claudian dynasty. During the civil wars of AD 68-69 following Nero's death, the Praetorian Guard became a key force in determining the Roman political landscape, leading to increasingly distorted operations of the principate and posing a serious challenge to the subsequent Flavian dynasty.

Overall, the rise and development of the Praetorian Guard during the Julio-Claudian period laid the historical "cause" for the subsequent century of the Empire's history. The many negative impacts generated by the Guard during this period would accumulate over time, becoming a significant factor in the decline of the Roman Empire.