軍功本為唐代官員追求升遷和發展的重要途徑，士人任官後投身軍事工作並非罕見，常被譽為「才兼文武」，成為後代效法的典範。安史之亂（755-763）後，職業武官權力擴張，壓縮文臣的軍事參與空間，同時削弱了朝廷對於軍隊的控制，威脅政權的安定。部分文官力圖扭轉此一趨勢，他們強調唐初以朝中高階文官統兵的傳統有助於駕馭軍隊，積極爭取統兵的機會，企圖打破「儒者不知兵」的印象。同時透過著書立說，提倡士人習兵，藉此展現兵學素養，以及對軍旅之事的意見。但是，所能產生的效果仍然有限。
由於缺乏武技與戰爭經驗，唐代後期的統兵文臣往往只能行使指揮之權，實際的戰鬥工作仍須仰賴武人。朝廷執政者派任文臣統兵，主要是為了展現對於兵權的控制，並非因為這些文官真有上陣作戰的能力。如此一來，文臣的軍事參與程度就與中央政府權威的高下有密切關係。黃巢之亂（875-884）以後，唐政府的權威一落千丈，軍隊不再受節制，成為軍閥爭取政權的資本，文臣乃無法在軍事上有所表現。

For officials during the Tang Dynasty, achieving military credits was an
important way to obtain promotions. For this reason, officials with civil
background would still choose to participate in military missions. In the first half
of the Tang Dynasty, the fact that some officials moved back and forth between
civil and military positions has attracted the attention of modern historians. After
the An Lushan Rebellion (755-763), however, professional soldiers expanded
their power, while the court failed to control the armies effectively. Under this
circumstance, most civil officials lost the opportunity to manage military affairs,
but some of them still attempted to follow the early Tang tradition. Through
providing military opinions to the court and advocating military learning among
literati, some civil officials tried to regain military leadership. In their mind,
appointing civil officials to military command positions could undermine the
influence of military men and strengthen the imperial authority. In the second
half of the Tang, thus, when the emperor tried to expand the central authority, he
could appoint civil officials to manage expeditions against insubordinate military
governors. However, due to the fact that late Tang civil elite usually lacked
military talents, most civil commanders failed to achieve substantial credits.
Thus, the efforts literati made to regain military leadership failed to increase the ruling power of Tang court. Along with the significant decline of Tang central
authority in the late ninth century, the military participations of civil officials
also came to an end.