Julius Caesar

Julius Caesar took part in 2 wars:
 * 1) Gallic Wars
 * 2) Civil War

Battle of the Sabis where Caesar was nearly captured
Julius Caesar was marching with 6 legions whilst 2 legions were trailing behind, a total of about 48000 soldiers. An estimated 25000 soldiers from four Belgic tribes were led by Boduognatus in the battle. Caesar's 6 leading legions were making camp near the river Sabis when they were suddenly attacked from across the river (the water was less than a meter deep). The swiftness of Boduognatus' sudden massed attack, the speed of his allied native footmen (Atrebates and Virumandui) together with the ferocity and skill at arms of his heavily armed Nerviians had completely routed Caesar's skirmishers and cavalry, overwhelmed his front and very nearly succeeded in taking the Roman camp and capturing Caesar himself. Caesar admits to losing all of his standards and most his centurions dead or felled by wounds. Only the arrival of the 2 trailing legions saved Caesar from complete annihilation.

Caesar's 2 failed invasions of Britain
Julius Caesar invaded Britain twice, in 55 and 54 BC. The first landing with 2 legions was opposed, but nevertheless Caesar managed to establish a camp. He then demanded hostages. Only two tribes felt sufficiently threatened by Caesar to actually send the hostages. In short, the campaign had not been a success. Caesar's ships were dashed against each other by tides and many were destroyed. If it had been intended as a full-scale campaign, invasion or occupation, it had failed, and even if it is seen as a reconnaissance-in-force or a show of strength to deter further British aid to the Gauls, it had fallen short.

The second time Caesar took 5 legions plus 2000 cavalry. This time the landing was unopposed. However, the next morning, as he prepared to advance further, Caesar received word from Atrius that, once again, his ships at anchor had been dashed against each other in a storm and suffered considerable damage. About forty, he says, were lost. The Romans were unused to Atlantic and Channel tides and storms, but nevertheless, considering the damage he had sustained the previous year, this was poor planning on Caesar's part. His men worked day and night for approximately ten days beaching and repairing the ships. After defeating a chieftain and obtaining promises of tribute, Caesar left, leaving not a single Roman soldier in Britain to enforce this settlement. Whether the tribute was ever paid is unknown.

Battle of Dyrrhachium where Caesar was completely routed
Having only built half the needed ships Caesar grew impatient and decided to gamble on sending half his army across, and to then have the ships travel back to Rome and transport the remainder. Caesar was able to sail through the blockade with the first half of his army. Bibulus however was able to block Caesar's attempt to sail his ships back to Italy, burning most of them. Caesar's blunder had put him in the worst possible position any army could find itself in. His army had no way to resupply from Rome due to the naval blockade, he couldn't resupply locally as Greece was pro-Pompey and closed their gates to Caesar, and his army was only at half strength. So dire was his situation that he made several attempts to discuss peace with Pompey but was refused at every channel. Realizing he was going to have to fight his way out, he attempted another winter blockade run back to Italy to lead his remaining forces to Greece. His luck was not with him and the rough seas and storms forced him back.Caesar had 15000 troops whilst Pompey had 45000. Pompey was in a strong position with the sea to his back and surrounded by hills that commanded the immediate area making an assault on the position impossible. Caesar ordered his engineers to build walls and fortifications to pin Pompey against the sea. Pompey responded with wall and fortifications of his own to prevent any further advancement. Two Gallic auxiliary were caught stealing the pay from legionaries, but managed to escape to Pompey. With these two men on his side, Pompey was able to discover the weakest point in Caesar's wall. A section to the south of the lines hadn't yet been completed and it was the only viable target for attack. Pompey mounted an attack of six legions against Caesar's line where it joined the sea and where Caesar's IX legion was stationed. Heavily outnumbering the Caesarian troops, the Pompeian army broke through the weakened fortifications, causing this segment of Caesar's force to pull back from the onslaught. Caesar swiftly reinforced the breach with twelve cohorts under Antony and then counter attacked, re-securing part of the wall and pushing Pompey's forces back. Although initially successful Pompey's forces were simply too numerous and they began to flank Caesar's right wing which buckled as it was threatened from the rear. As the wing collapsed, Caesar's army began to rout. At first Caesar personally tried to stem the retreat, but then realised the potentially disastrous danger his army faced and instead began to co-ordinate the withdrawal of his army. Pompey ordered a halt, suspicious of a trap. Had Pompey ordered a pursuit, it would have been the end for Caesar. This caused Caesar to remark, "The day was theirs had there been anyone among them to take it."

Conclusion: Not a great commander.