Weapon A weapon is an instrument used for the purpose of causing harm or damage to persons , animals or structures . Weapons are used in hunting , attack , self - defense , or defense in combat and range from simple implements like clubs and spear s to complicated modern machines such as intercontinental ballistic missile s . One who possesses or carries a weapon is said to be armed . In a broader context weapons include anything used to gain an advantage over an adversary or to place them at a disadvantage . Examples include the use of siege s , tactic s , and psychological weapons which reduce the morale of an enemy . History . Prehistoric . Very simple weapon use has been observed among chimpanzee s , leading to speculation that early hominids began their first use of weapons as early as five million years ago . These would have been wooden clubs , spears , and unshaped stones — none of which would leave an unambiguous record . The earliest unambiguous weapons are : Ancient and classical . Ancient weapon s were evolutionary improvements of late neolithic implements , but then significant improvements in materials and crafting techniques created a series of revolutions in military technology : The development of metal tools , beginning with copper during the Copper Age ( about 3 , 300 BC ) and followed shortly by bronze led to the Bronze Age sword and similar weapons . The first defensive structures and fortifications appeared in the Bronze Age . Indicating an increased need for security . Weapons designed to breach fortifications followed soon after , for example the battering ram was in use by 2500 BC . Although early Iron Age sword s were not superior to their bronze predecessors , once iron - working developed - around 1200 BC in Sub - Saharan Africa , iron began to be used widely in weapon production because iron ore was much more readily available than the copper and tin required to create bronze . Cavalry developed once horses were bred to support the weight of a man . The horse extended the range and increased the speed of attack , but was not a weapon as much as it provided an enhanced capability . Domestication of the horse and widespread use of spoke d wheels by ca . 2000 BC , led to the light , horse - drawn chariot . The mobility provided by chariots were important during this era . Spoke - wheeled chariot usage peaked around 1300 BC and then declined , ceasing to be militarily relevant by the 4th century BC . Ships built as weapons or warship s such as the Trireme s were in use by the 7th century BC . These ships were eventually replaced by larger ships by the 4th century BC . Tactics and organization . As technology advanced , so did the level of organization of peoples eventually leading to the development of empires and armies . Professional armies allowed aggressive , militaristic states to emerge . While early Greek armies focused on physical training and individual ability , a key advancement of the Roman army was the development complex tactic s used to gain additional advantage over their enemies . Middle Ages . European warfare during the middle ages was dominated by elite groups of knights supported by massed infantry ( both in combat and ranged roles ) . They were involved in mobile combat and sieges which involved various siege weapon s and tactics . Knights on horseback developed tactics for charging with lances providing an impact on the enemy formations and then drawing more practical weapons ( such as swords ) once they entered into the melee . Whereas infantry , in the age before structured formations , relied on cheap , sturdy weapons such as spear s and billhooks in close combat and bows from a distance . As armies became more professional their equipment was standardized and infantry transitioned to pikes in conjunction with smaller side - arms ( short sword ) . In Eastern and Middle Eastern warfare similar tactics were developed independent of European influences . The introduction of gunpowder from the Far East at the end of this period revolutionized warfare . Formations of musketeers , protected by pikemen came to dominate open battles , and the cannon replaced the trebuchet as the dominant siege weapon . Early modern . The European Renaissance marked the beginning of the implementation of firearms in western warfare . Gun s and rocket s were introduced to the battlefield . Firearm s are qualitatively different from earlier weapons because they release energy from combustible propellant s such as gunpowder , rather than from a counter - weight or spring . This energy is released very rapidly and can be replicated without much effort by the user . Therefore even early firearms such as the arquebus were much more powerful than human - powered weapons . Firearms became increasingly important and effective during the 16th century to 19th century , with progressive improvements in ignition mechanisms followed by revolutionary changes in ammunition handling and propellant . During the U . S . Civil War various technologies including the machine gun and ironclad warship emerged that would be recognizable and useful military weapons today , particularly in limited conflicts . In the 19th century warship propulsion changed from sail power to fossil fuel - powered steam engines . The age of edged weapons ended abruptly just before World War I with rifled artillery . Howitzer s were able to destroy masonry fortresses and other fortifications . This single invention caused a Revolution in Military Affairs ( RMA ) and established tactics and doctrine that are still in use today . " See Technology during World War I for a detailed discussion . " An important feature of industrial age warfare was technological escalation - innovations were rapidly matched through replication or countered by yet another innovation . The technological escalation during World War I ( WW I ) was profound , producing armed aircraft and tank s . This continued in the inter - war period ( between WW I and WW II ) with continuous evolution of all weapon systems by all major industrial powers . Many modern military weapons , particularly ground - based ones , are relatively minor improvements of weapon systems developed during World War II . " See military technology during World War II for a detailed discussion . " Modern . Since the mid - 18th century North American French - Indian war through the beginning of the 20th century , human - powered weapons were reduced from the primary weaponry of the battlefield yielding to gunpowder - based weaponry . Sometimes referred to as the " Age of Rifles " , this period was characterized by the development of firearms for infantry and cannons for support , as well as the beginnings of mechanized weapons such as the machine gun , the tank and above all the wide introduction of aircraft into warfare , including naval warfare with the introduction of the aircraft carrier s . World War I marked the entry of fully industrialized warfare as well as weapons of mass destruction ( e . g . chemical and biological ) , and weapons were developed quickly to meet wartime needs . Above all it promised to the military commanders the independence from the horse and the resurgence in maneuver warfare through extensive use of motor vehicles . The changes that these military technologies underwent before and during the Second World War were evolutionary , but defined the development for the rest of the century . World War II however , perhaps marked the most frantic period of weapons development in the history of humanity . Massive numbers of new designs and concepts were fielded , and all existing technologies were improved between 1939 and 1945 . The most powerful weapon invented during this period was the atomic bomb , however many more weapons influenced the world in different ways . Since World War II . After World War II and with the onset of the Cold War , constant technological advancement of weapons was institutionalized . Countries engaged in a competitive race to develop more lethal weapons and counter - weapons . This arms race has continued into the current era and remains a drain on the resources of most nations . Notable development in weaponry since World War II has been the combination and further development of nuclear weapon s and ballistic missile s . Resulting in the development of the intercontinental ballistic missile ( ICBM ) . The Cold War race for larger and more effective weapons lead to the refinement of the atomic weapons ( hydrogen bomb ) and multiple warhead missiles . The mutual possession of ICBMs by the United States and the Soviet Union created an environment of mutually assured destruction ( see below ) . The indiscriminate nature of the destruction has made nuclear - tipped missiles essentially useless for the smaller wars fought since . However computer - guided weaponry of all kinds , from precision - guided munition s ( or " smart bombs " ) to computer - aimed tank rounds , have greatly increased weaponry ' s accuracy . Being able to prepare , maneuver and attack before the enemy can detect the threat and respond can provide a decisive advantage . The element of surprise has long been recognized as a tactical advantage . Modern technology has increased this though sophisticated night vision technology allowing maneuvering and engagement at night when the enemy , not as well equipped , has limited visibility . Advanced technological surveillance and intelligence gathering methods through the use of unmanned aerial vehicle s is a benefit to prevent surprise and identify targets . Coordination of forces is necessary in order to control disparate forces effectively . Modern communications , if unjammed and not intercepted are a substantial advantage . Once targets or strategic objectives are identified it is necessary to prepare detailed plans for individual forces to follow . This can be a time consuming process that modern armies are using computers to overcome . Successful integration of automated planning can result in more responsive use of existing weapons platforms against the enemy . Cyberwarfare is an emerging weapon that recognizes the vulnerabilities of enemy infrastructure , intelligence apparatus , and communications systems and provides from their disruption . Nuclear age and beyond . Since the realization of Mutually Assured Destruction ( MAD ) , the nuclear option of all - out war is no longer considered a survivable scenario . During the Cold War in the years following World War II , both the United States and the former Soviet Union engaged in a nuclear arms race . Each country and their allied blocks continually attempted to out - develop each other in the field of nuclear armaments . Once the joint technological capabilities reached the point of being able to ensure the destruction of the entire planet ( see Mutually Assured Destruction ) then a new tactic had to be developed . With this realization , armaments development funding shifted back to primarily sponsoring the development of conventional arms technologies for support of limited war s rather than nuclear war .