A frontal assault is a military tactic which involves a direct, full-force attack on the front line of an enemy force, rather than to the flanks or rear of the enemy. It allows for a quick and decisive victory, but at the cost of subjecting the attackers to the maximum defensive power of the enemy; this can make frontal assaults costly even if successful, and often disastrously costly if unsuccessful. It may be used as a last resort when time, terrain, limited command control, or low troop quality do not allow for any battlefield flexibility. The risks of a frontal assault can be mitigated by the use of heavy supporting fire, diversionary attacks, the use of cover (such as smokescreens or the darkness of night), or infiltration tactics.

Frontal assaults were common in ancient warfare, where heavy infantry made up the core of armies such as the Greek phalanx and the Roman legion. These dense formations, many ranks deep, would utilize their weight in numbers to press forward and break enemy lines. In medieval warfare, heavy cavalry such as mounted knights relied on frontal assaults for easy victories against infantry levies.

These tactics waned as the defensive quality of infantry increased, especially with the introduction of firearms. Both heavy infantry and heavy cavalry were replaced with lighter, more maneuverable troops.

Yet even in Napoleonic warfare, a frontal assault by cavalry against a thin line could be effective when conditions were right, or even by infantry if the enemy was shaken or weakened by preceding attacks. But as firepower increased, as with the introduction of the rifle, successful frontal assaults against a prepared enemy became rare. They continued to be attempted, however, as alternative tactics that could achieve a decisive victory for the attacker were not developed.

During the American Civil War, it took some time for generals on both sides to understand that a frontal assault against an enemy who was well entrenched or otherwise held a strong defensive position was unlikely to succeed and was wasteful of manpower.

During World War I, advances in machine guns and artillery greatly increased defensive firepower, while trench warfare removed almost all options for battlefield maneuver. This resulted in repeated frontal assaults with horrific casualties. Only at the end of the war, with the introduction of tanks, infiltration tactics, and combined arms, were the beginnings of modern maneuver warfare found as a way to avoid the necessity of frontal assaults.