In the Prussian army, cuirassier units were the senior cavalry and generally held in highest regard. At the beginning of the Franco-Prussian War (1870-1), the Prussian army list had two guard and eight line regiments, and these were probably the best equipped, mounted and trained heavy cavalry regiments in Europe. Except for the Garde du Corps and Guard Cuirassiers, the regiments were named after their place of recruiting, following the tradition of the Napoleonic Wars: 1st Silesian, 2nd Pomeranian, 3rd East Prussian, 4th Westphalian, 5th West Prussian, 6th Brandenburg, 7th Magdeburg and 8th Rhenish. Each consisted of four squadrons of 150 men, and a 200-man depot squadron.

According to Prussian cavalry rules of 1860, the requisite height for service in the cuirassiers was at least 170 cm/5 ft 7 in for men and 157.5 cm/62 in for horses. For Guard Cuirassiers, they were 175 cm and 162 cm/5 ft 9 in and 64 in respectively. For comparison, the minimum heights of men and mount for dragoon and uhlan units were 167 cm/5 ft 6 in and 155.5 cm/61 in, and for hussars and their horses 162 cm/5 ft 4 in and 152.5 cm/60 in. For light guard horsemen, the line was set at 172 cm/5 ft 8 in for men and 156 cm/61 in for their steeds. Cuirassier and dragoon regiments were mounted on Holstein, Hanover and Magdeburg breed horses.

The height of horses is measured from the withers in centimetres/inches or hands, a hand being equal to 10.16 cm/4 in. In horses of similar proportions a difference in height of 1 cm (less than ½ in), though seemingly negligible, could mean a difference in weight of 10-20 kg/22-44 lb. A Guard Cuirassier horse 162 cm/64 in tall could weigh up to 600 kg/330 lb while a hussar horse 152.5 cm/60 in tall would be about 450 kg/990 lb.

In the initial phase of the Battle of Mars-la-Tour, on 16 August 1870, a Prussian cavalry brigade made up of the 7th Magdeburg Cuirassiers and the 16th Uhlans executed a charge against the French infantry and artillery which became known as the todesritt (death ride). The French infantry threatened to attack the weak Prussian left wing near Vionville, jeopardizing further Prussian advances. As reinforcements failed to materialize, General Alvensleben ordered General von Bredow to charge with his brigade, consciously sacrificing them to halt the enemy until his own troops arrived. Von Bredow led his men into the charge spread out in a line, with the cuirassiers under Major Count von Schmetow on the left and the uhlans on the right, in all about 700 men. Under fire from cannon and machine-guns, the Prussians pierced the French defensive lines and cut down the artillery crews and the infantry around them. Carried away by their success, they attacked the French troops behind the first line, but were surprised by a division of enemy cavalry and routed. Less than half the brigade returned – 104 cuirassiers and 90 uhlans. The charge held the French back until the end of the day, and removed the danger to the Prussians’ left wing.

Fearing new attacks, the French brought in another cavalry division, while the Prussians used their cavalry to secure the arrival of reinforcements. At Mars-la-Tour, 5,000 French and Prussian cuirassiers clashed in the greatest cavalry battle of the war.