In addition to being experts in explosives, demolition, and construction, combat engineers are also trained warfighters. In fact, engineer soldiers have been integral to armies since at least 1884 BC, when the Greeks used their famous giant wooden horse to infiltrate the city of Troy and deliver the deathblow that finally ended the 10-year Trojan War.

In 332 BC, Alexander the Great's engineers built siege towers to topple the Persian city of Tyre. During the First Jewish-Roman War, Roman engineers spent two months constructing a giant ramp in order to ascend a mountain and sack the fortress of Masada. Nearly 2,000 years later, British engineers tunneled across no-man's land and set off a series of bombs underneath the German trenches. The detonations, which initiated the Battle of the Somme, were so massive that they remain among the largest non-nuclear explosions ever recorded.

Sappers and Siege Warfare in the Age of Cannons

By the 1600s, powerful siege cannons had become an essential part of every major army's arsenal. These massive weapons could hurl heavy iron cannonballs over great distances with devastating effect against enemy walls and fortifications.

As a result, castles and other seemingly impregnable fortifications could often be reduced once siege artillery was brought within effective range.

The challenge was getting these enormous guns close enough to the target. As they advanced, the cannons and their crews were exposed to enemy artillery and musket fire, making a direct approach extremely dangerous.

The solution was the employment of specially trained soldiers known as sappers. The word sapper comes from the French verb saper, meaning "to undermine" or "to dig beneath." These engineer soldiers dug a series of zigzag approach trenches that allowed troops and siege guns to move steadily toward the enemy while remaining largely protected from direct fire. Experienced engineer officers became so proficient at planning these operations that they could often estimate with remarkable accuracy how many days their sappers would need to complete the trenches and bring the siege artillery into position.

Once the siege guns opened fire and began smashing the enemy's walls with their massive projectiles, the defenders often realized that their fortifications would eventually be breached. In many cases, rather than endure a costly assault, they chose to surrender.

The World War I Introduction of "Pioneers"

While British engineers were perfecting their tunneling skills in WWI, German engineers were forming experimental units of combat engineers known as "pioneers." Armed with explosives and flamethrowers, these pioneer units specialized in destroying enemy fighting positions. Other nations recognized their effectiveness and eventually followed suit. Today's German Army still refers to its Combat Engineers as "Pioniers."

Combat Engineers in World War II   American pioneer units proved equally as effective in World War II as their World War I German counterparts.

The Battle of the Bulge in the European Theater, December 16, 1944 - January 16, 1945, was the largest and bloodiest single battle fought by the United States in World War II, and the third-deadliest campaign in American history. This German offensive was intended to stop Allied use of the Belgian port of Antwerp and to split the Allied lines, allowing the Germans to encircle and destroy each of the four Allied armies and force the western Allies to negotiate a peace treaty in the Axis powers' favor. The Allied victory, despite early German successes, was attributed to the quick arrival of reinforcements, German logistical issues, and the tenacious defense of the vital road junctions at Bastogne and St Vith. A lesser known story is one of many small engineer units, with courage and initiative, who harassed and delayed a huge, strong, and eponymous German battle group (SS-Kampfgruppe Peiper) of 117 tanks, 700 other vehicles, and 5,000 troops. This, in combination with the factors named earlier, led to the defeat of this battle group and the loss of all its tanks and vehicles.

Combat Engineers in Operation Desert Storm, Operation Iraqi Freedom, and the Global War on Terror

Combat engineers are also the go-to experts when enemy obstacles need to be cleared or destroyed. During the Gulf War, combat engineers cut paths through Saddam Hussein's so-called "impenetrable barrier" - a wall of minefields, wire obstacles, and fire trenches along the Iraq-Kuwait border. Their quick work was praised by General Norman Schwarzkopf, commander of all American forces during the invasion, who famously said, "They went through the first barrier like it was water."

Later, during Operation Iraqi Freedom, combat engineers were called on again to lead the way. Across the war's urban battlefields, where IEDs posed the biggest threat to American troops, engineers were often tasked with conducting route clearance missions. In this role, engineers cleared paths for other soldiers, sailors, and Marines to follow on foot and in vehicles and engage the enemy without their movement being restricted by the additional risk of concealed bombs.

When they weren't conducting route clearance, combat engineers deployed to the battlefields of the War on Terror often filled in as explosive disposal experts. Though every branch has their own specially trained explosive ordnance disposal technicians, IEDs were so ubiquitous in Iraq and Afghanistan that engineers were relied upon to use their knowledge of explosives to take on some of the workload. And none of the forward operating bases or combat outposts that dotted the battlefields of the Global War on Terror would exist without the good work of combat engineers.