Warfare
The Germanic idea of warfare is quite different from the pitched battles fought by Rome and Greece. Instead the Germanic tribes focused on raids.
The purpose of these is generally not to gain territory, but rather to capture resources and secure prestige. These raids are conducted by irregular troops, often formed along family or village lines, in groups of 10 to about 1,000. Leaders of unusual personal magnetism could gather more soldiers for longer periods, but there is no systematic method of gathering and training men, so the death of a charismatic leader could mean the destruction of an army. Armies also often consist of more than 50 percent noncombatants, as displaced people would travel with large groups of soldiers, the elderly, women, and children.
Thus a typical Germanic force might consist of 100 men with the sole goal of raiding a nearby Germanic or foreign village. When the Germanic Tribes fight pitched battles, the infantry often adopts wedge formations, each wedge being led by a clan head.
Whatever their particular culture, the Germanic tribes generally prove themselves to be tough opponents, racking up several victories over their enemies. They sometimes use massed fighting in tightly packed phalanx-type formations with overlapping shields, and employ shield coverage during sieges. In open battle, they sometimes used a triangular "wedge" style formation in attack. Their greatest hope of success lay in 4 factors: (a) numerical superiority, (b) surprising the Romans (via an ambush for example) or in (c) advancing quickly to the fight, or (d) engaging the Romans over heavily covered or difficult terrain where units of the fighting horde could shelter within striking distance until the hour of decision, or if possible, withdraw and regroup between successive charges. The Battle of the Teutoburg Forest contains all four: surprise, a treacherous defection by Arminius and his contingent, numerical superiority, quick charges to close rapidly, and favorable terrain and environmental conditions (thick forest and pounding rainstorms) that hindered Roman movement and gave the warriors enough cover to conceal their movements and mount successive attacks against the Roman line. Three Roman legions were ambushed and destroyed by an alliance of Germanic tribes headed by Arminius at the Battle of the Teutoburg Forest in 9 AD, the Roman Empire made no further concentrated attempts at conquering Germania beyond the Rhine.
Though often defeated by the Romans, the Germanic tribes are remembered in Roman records as fierce combatants, whose main downfall is that they fail to join together into a collective fighting force under a unified command, which allow the Roman Empire to employ a "divide and conquer" strategy against them. On occasions when the Germanic tribes work together, the results are impressive.
Germanic tribes eventually will overwhelm and conquer the ancient world, giving rise to modern Europe and medieval warfare.
https://en.wikipedia.org/wiki/Laager#Circle_the_wagons
https://en.wikipedia.org/wiki/Gothic_and_Vandal_warfare
https://en.wikipedia.org/wiki/Fire_ship