history of ODST(also known as obital drop shock troopers(or also known as hell jumpers))

Origins
The idea of inserting highly trained troops behind enemy lines from high altitudes has its roots in the paratroopers of 20th and 21st century fame, who dropped frequently behind enemy lines to capture strategically important targets in anticipation for a larger advance by more conventional and numerous military forces.

Such troops were first used prior to World War II by Italian and Soviet forces, but the first serious application of the doctrine was seen in 1940 by the German Air Force in World War II to overrun the Allied positions in Denmark, the Netherlands and the legendary Eben Emael fortress in Belgium. Paratroops were also used to capture the entire island of Crete. Later, during the Battle of Normandy known as Operation Overlord on June 6, 1944, when two American Airborne Divisions and one British Airborne Division landed behind enemy lines in Normandy, France on D-Day and again in Operation Market Garden. Although they were only marginally successful, they proved the concept of paratroops as useful and effective in large scale warfare.

While the concept of dropping human soldiers from orbit had been around since the early 21st century, the establishment of the UN Marine Corps in 2163, would be the historic first deployment of the future 105th infantry in the Martian Campaign against the Neo-Communist Koslovics. The UN Marines historic first drop onto Mars in support of UN led war against the Koslovics and the Frieden forces not only proved the feasibility of such an option, but also the effectiveness of deploying soldiers from orbit. The success of the Argyre Planitia Campaign by the UN, and its participants of the first drop onto martian soil would become the predecessors, or early members, to the modern ODST units.

At the conclusion of the Rain Forest Wars and the Jovian Moons Campaign the Orbital Drop Shock Troopers was a fully established force and participated in every high risk operation during those conflicts, however at the conclusion of these conflicts in 2170 with the signing of the Callisto Treaty and the subsequent years that followed, the ODSTs saw little action as more political, and more important issues such as overpopulation and famine and a massive military with no purpose gripped the postwar nations of Earth. The first major combat reemergence of the ODSTs occurred in 2490 during the beginnings of the civil conflict between the UEG and the Insurrection. For the years leading up to 2525 the ODSTs would once again conduct high risk operations against the Insurrectionist, to either stop the enemy before they could carry out attacks against supporters, and officials of the Earth Government or to cut off major suppliers to the Insurrectionists.

Human-Covenant WarMain article: Human-Covenant War
On November 1, 2525, the UNSC moved into a full alert status after the devastating and horrifying first contact with the Covenant at Harvest; this marked a change in objectives for the ODSTs, who up until that point had been fighting the Insurrectionists. As humanity's military turned to meet the threat of the Covenant, divisions of ODSTs prepared to participate in the most critical engagements in the war and also to conduct the riskiest missions in the history of mankind. The Battle of Hat Yai marked one of the first deployments of ODSTs against Covenant ground forces; although the planet was lost in the ensuing conflict, the ODSTs were successfully extracted before the UNSC retreated.

Not long after the Harvest Campaign, the ODSTs participated in the First Battle of Arcadia where they assisted Marine forces and SPARTAN-II Red Team in defending the capital city from Covenant ground forces, thus allowing the evacuation of the civilian population. Having successfully kept Covenant forces from occupying the city, the Corps began launching multiple assaults on the Covenant's bases of operations to reclaim the planet. Several ODST battalions joined the Spirit of Fire's rescue operation after retaking the planet and soon participated in the Battle of the Shield World.

Following the enactment of the Cole Protocol in 2535, ODST combat teams were tasked with boarding commercial and private vessels and purging their navigation databases. During one of these routine operations, a group of ODSTs aboard the UNSC Midsummer Night were captured and taken to the Rubble. They, in conjunction with SPARTAN-II Gray Team, would later defeat a Kig-yar plan to trick the inhabitants of the Rubble out of their navigation data, which could compromise the location of Earth.

As the war with the Covenant continued to progress, the ODSTs would go on to participate in many engagements; among these were the Battle of Jericho VII, an assassination mission on Heian, the Battle of Skopje, the Battle of Sigma Octanus IV, the Battle of New Jerusalem, the Battle of Tribute, and the Battle of Ariel. The numerous campaigns and operations in which the ODSTs participated throughout the long war all pale in comparison to the Fall of Reach in 2552, during which countless ODSTs lost their lives defending strategic locations on the planet.

During the initial invasion of Reach, a large contingent of ODSTs were stationed on the UNSC Pillar of Autumn. As the planet fell to the Covenant onslaught, the vessel made a blind Slipspace jump away from the Epsilon Eridani system, discovering the long-abandoned Installation 04. During the Battle of Installation 04, shock troopers led by Major Antonio Silva and First Lieutenant Melissa McKay, operated as a guerrilla force by conducting hit-and-run operations against the forces of the Covenant's Fleet of Particular Justice.

Fresh from the disastrous loss of Reach, the ODSTs participated in the most significant battle of the entire war: the Battle of Earth. The battle began on October 20, 2552, when a smaller-than-expected Covenant fleet led by the Prophet of Regret jumped into the Sol System. ODST combat teams, along with the Marines, began engaging Covenant forces on the Orbital Defense Platforms Cairo, Athens, and Malta. Despite the ODSTs' valiant efforts, Malta and Athens were destroyed. As the Covenant ship carrying the Prophet of Regret landed over the African mega-city of Mombasa, teams of ODSTs were deployed over the city from orbit in an attempt to board the carrier; before the teams could reach the target, however, the carrier jumped into Slipspace. Only a single squad managed to safely land in the city to carry out the retrieval of the Superintendent's data.

After Regret's unexpected retreat from New Mombasa, members of the 7th Shock Troops Battalion would later drop from the In Amber Clad onto Installation 05 during the operation to capture the Prophet of Regret. Most of these troopers would perish during the initial firefights against the Covenant, and only a few would escape back to Earth with Lieutenant Commander Miranda Keyes to lead a resistance against the Covenant occupation forces.

Overall, the defense of Earth was one of the largest campaigns the ODSTs fought in during the entire war. The fighting spread across the globe and in space as the Fleet of Furious Redemption and the Prophet of Truth's own fleet attacked the remnants of the Orbital Defense Grid. The fleets soon deployed troops throughout the continents of North America, South America, Europe and Asia. The Battle of Cleveland is one example of the ODSTs' participation during the war on Earth. Two ODSTs from the 2nd Shock Troops Battalion fought alongside a detachment of Marines in the Battle of Pawas. Troopers T. Rymarr and S. Hartley were tasked with calculating the crash site of John-117 on Earth, while a Marine battalion was tasked with defending a narrow corridor between Covenant and UNSC forces in Pakistan. Bravo-21 and numerous Marines were killed in the clash, while Bravo-22 was injured along with some of the other surviving Marines. Their actions successfully allowed HIGHCOM to track and locate the Spartan.

After the opening of the Artifact in November of 2552, the 11th Marine Force Reconnaissance/ODST, stationed aboard the UNSC Forward Unto Dawn, fought alongside the Master Chief, during Operation: BLIND FAITH. Men and women from this battalion were also some of the first humans to travel outside the Milky Way Galaxy, during the Battle of Installation 00. One such assault happened during a mission to destroy numerous Covenant anti-aircraft artillery platforms overlooking a desert. These AA guns were destroyed by the ODSTs, allowing the UNSC Forward Unto Dawn to successfully land near the Cartographer building.[10] During the last battle of the Ark campaign - the last battle of the war - ODSTs were again airlifted into combat. This time, they punched holes in Covenant armor and artillery positions to allow SPARTAN-117 and the Arbiter to eliminate the Prophet of Truth.

Battle Dress Uniform
The ODST Battle Dress Uniform is the signature piece of equipment used by the ODSTs - the armor is vacuum-rated, capable of extravehicular activity for fifteen minutes. The ODST BDU has been in use for well over 50 years by the 105th, and remains untouched by its ability to protect its wearer during the toughest operations.

Human Entry Vehicles
The Single Occupant Exoatmospheric Insertion Vehicle abbreviated SOEIV is a tear-drop shaped pod made of Titanium-A, Lead Foil and coated with ceramic skin. The SOEIV is the signature piece of equipment used by the ODSTs and is known for its risks and intense heat which has garner the ODST nickname Helljumpers.

Armed Assault Boats
Armed Assault Boats were aircraft used by the UNSC Navy and Marine Corps, to deploy troopers for air assaults. However, the armed assault boats proved to be ineffective, taking heavy fire once within ground firing range and were also very slow. At some point they were replaced by the SOEIV.