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.
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.
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.
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.