After the death of Commodus in the previous century the Roman Empire was plunged into a civil war. When the dust settled, Septimius Severus emerged as emperor, establishing the Severan dynasty. Unlike previous emperors, he openly used the army to back his authority, and paid them well to do so. The regime he created is known as the MilitaryMonarchy as a result. The system fell apart in the 230s, giving way to a fifty-year period known as the Military Anarchy or the Crisis of the Third Century, where no fewer than twenty emperors held the reins of power, most for only a few months. The majority of these men were assassinated, or killed in battle, and the empire almost collapsed under the weight of the political upheaval, as well as the growing Persian threat in the east. Under its new Sassanid rulers, Persia had grown into a rival superpower, and the Romans would have to make drastic reforms in order to better prepare their state for a confrontation. These reforms were finally realized late in the century under the reign of Diocletian, one of them being to divide the empire into an eastern and western half, and have a separate ruler for each.
An early type of hot air balloon used for military signalling, known as the Kongming lantern was said to be invented by Zhuge Liang.
The repeating crossbow or semi-automatic crossbow is an improved version of a model that first appeared during the Warring States Period (though there is debate whether the original Warring States Period bow was semi-automatic, or rather shot multiple bolts at once). Nevertheless, Zhuge's version could shoot farther and faster.
Some sources report that Zhuge Liang invented a primitive land mine type device.
A mysterious but efficient automatic transportation device (initially used for grain) referred to as the "wooden ox and flowing horse" (木牛流馬) also invented by Zhuge, which is sometimes identified with the wheelbarrow.