李牧对秦军的战绩，是大家有目共睹的：
https://en.wikipedia.org/wiki/Qin%27s_wars_of_unification
In 233 BC, Huan Yi's army crossed Mount Taihang and conquered the Zhao
territories of Chili (赤丽) and Yi'an (宜安), both located southeast of
present-day Shijiazhuang, Hebei.
the Qin army under Huan Yi engaged the Zhao army commanded by General Li Mu
at the Battle of Fei in which the Qin sustained a massive defeat and nearly
lost all their forces.
In 232 BC, the Qin forces split into two groups to attack Fanwu (番吾;
present-day Lingshou County, Hebei) and Langmeng (狼孟; present-day Yangqu
County, Shanxi), but were defeated again by the Zhao army led by Li Mu.
李牧对秦军二战二胜，而肥之战的经过如下：
https://en.wikipedia.org/wiki/Battle_of_Fei_(233_BCE)
Li Mu felt that the Qin army's morale was high after its earlier victories,
so it would be unwise for Zhao to attack Qin then. He ordered his troops to
strengthen their fortifications and defences while waiting for an opportunity
to launch an counteroffensive.
As the bulk of the Qin army had left to attack Fei, the Qin camp was poorly
defended so Li Mu seized the opportunity to order his troops to launch an
offensive on the Qin camp. The Zhao forces scored a major victory in the
ensuing battle and captured several prisoners-of-war and supplies.
As Li Mu predicted that Huan Yi would retreat from Fei to save the camp,
he ordered his men to lay an ambush on Huan Yi's retreat route. Huan Yi's
retreating troops fell into the ambush.
Qin sustained over 100,000 casualties in the battle
到了秦灭赵之战，李牧一样打得有声有色：
In 229 BC, Qin took advantage of the situation to launch a pincer attack
from the north and south on Handan, the Zhao capital.
On the Zhao side,
Li Mu and Sima Shang (司马尚) were put in command of the Zhao army.
Li Mu ordered his troops to build defensive structures and avoid direct
confrontation with the enemy. The Qin forces were unable to advance further
and both sides reached a stalemate.