法兰克王国与拜占庭帝国的互动关系向来是学界关注的重点，尤其在现 今西方学界所强调的“古典文明的终结与地中海世界的裂变”语境之下，双 方在地中海世界变化进程中均扮演着重要的角色。八至九世纪是法兰克与拜 占庭互动较为密切而频繁的时期，联系双方的纽带则是意大利半岛，双方围 绕着意大利控制权的问题展开了一系列斗争与协作。查理曼上台后，他将北 意大利纳入法兰克王国版图之中，建立起长期且稳定的管理制度与官僚队伍。 在中意大利，其政策是扶持罗马教宗并与之结盟。至于南意大利，查理曼考 虑到拜占庭在南意的领土，故法兰克王国在南意的扩张步伐止于贝内文托公 国。查理曼的意大利政策主要有两大指向：一是在意营造良好的政治生态， 二则是同罗马教宗结盟，为自身在西方世界的统治披上合法性外衣。反观拜 占庭，它在意大利的地位一路下滑，丧失前哨站拉文纳后，拜占庭只能龟缩 于以卡拉布里亚、西西里为主体的南意大利。为了维系南意大利的领土，拜 占庭采取拉拢罗马教宗、缔结婚姻联盟、培养卫星国等手段与法兰克周旋。 然而，由于法兰克王国、罗马教宗、伦巴德残余势力与诸多独立公国势力在 半岛并存，形势复杂，加之东部阿拉伯人的进攻，令拜占庭难以实现目标， 一度陷入被动的境地。800 年查理曼称帝加冕后，拜占庭同意了法兰克方缔 结婚姻联盟的请求，但囿于国内政治动乱未能实现。尼斯弗鲁斯上台后，拜 占庭与法兰克和谈破裂，双方随即在亚德里亚海域爆发了长达九年的意大利 战争。最终，查理曼“以土地换名誉”，将威尼斯与达尔马提亚返还拜占庭， 而拜占庭对查理曼帝号予以承认。从一系列半岛争端可见，意大利半岛对于 双方而言均具有重大意义。对查理曼以及整个法兰克王国的发展道路而言， 在意大利建立起的优势地位为查理曼称帝提供了便利，也为帝号名衔得到东 方的承认提供了筹码；对于拜占庭帝国而言，意大利半岛既是同西方建立联 系的纽带，也是重振罗马帝国霸权的基础。但拜占庭在意大利的优势早已不 复存在，它不得不作出让步，放弃查士丁尼统治整个地中海的政策，进而选 择与法兰克政权并存，并逐步退出西方世界。基于两国的目标与未来道路， 双方达成了三次共识，分别是 781 年联姻，801 年联姻以及 812 年的和谈， 主要围绕意大利部分领土控制权与查理曼皇帝名衔问题展开。查理曼名衔得 到拜占庭承认后，新的东西方格局正式建立起来：法兰克王国统治西方世界， 而拜占庭将帝国重心转移到东部地中海。双方虽达成了短暂的共识，长期来 看双方的对立、疏离态势是客观存在的。最终两国分治地中海，东西相互制 衡的长期状态逐步形成。

During the eighth and ninth century, the Frankish kingdom and the Byzantine Empire established a long-time interaction, the key of which is Italy Peninsula. After Charlemagne had conquered Lombards, the Northern Italy became the territory of the Frankish kingdom and the Central Italy was controlled. As regard the Southern Italy, Duchy of Benevento also submitted to Charlemagne. On the other hand, the domination of Byzantine was fading continuously. Byzantine lost Exarchate of Ravenna in 751, which is the outpost of Byzantine-Italy. The Pope of Roman also quitted the alliance with the Byzantine emperor for the Iconoclasm led by Leo Ⅲ. Eventually, Byzantine only occupied some regions of Southern Italy, including Calabria and Sicilia. To seized the lordship of the Italy, the Frankish kingdom and the Byzantine empire had a series of interaction upon the Italy Peninsula, which highlight the conflicts and the consensuses of each. Sooner after Charlemagne had controlled Italy and established a firm alliance with the Pope of Roman, he was crowned emperor by Pope Leo Ⅲ on Christmas Day in 800, which meant Charlemagne had became the leader of western Christendom. On the other hand, Byzantine emperors strived to maintain the political order and its privilege in Italy. In 812, Nicephorus Ⅱ made peace and recognised Charlemagne as western emperor. At the same time, Byzantine attached more importance to the affairs of the East Mediterranean sea . This series of struggles reflected the alienation trend between the Frankish Kingdom and the Byzantine Empire. Nevertheless, they also reached consensus on Italy Peninsula. In conclusion, the Frankish Kingdom and the Byzantine Empire administered different part of Mediterranean sea, which established a pattern of balance.