Armed with twelve 10.5 cm SK L/45 guns, Karlsruhe had a top speed of 28.5 knots (52.8 km/h; 32.8 mph), which allowed her to escape from British cruisers during her career.

Some question was given to revising the armament, but all of the proposals to increase the number or size of the main battery would have resulted in considerable delays.

The side belt armor was increased in height to improve the ships' resistance to enemy fire, and fuel oil was introduced as part of the propulsion system on an experimental basis.

Additional protection was provided by a curved armor deck that sloped downward at the sides of the ship and connected to the bottom edge of the belt.

[2][5] On 1 July, Karlsruhe reached Saint Thomas in the Danish West Indies; there the ship received news of the assassination of Archduke Franz Ferdinand and his wife in Sarajevo three days before.

The ship then proceeded to Port-au-Prince, Haiti to protect German nationals during a period of civil unrest in the city from 5 to 9 July.

Karlsruhe was to have gone to Veracruz and then to the opening ceremonies of the Panama Canal, but Köhler decided against this since the July Crisis over Ferdinand's assassination was at its peak, and there were numerous British and French warships already present for the celebration.

On 30 July, Karlsruhe left the port, initially keeping close to shore before proceeding to the isolated Cay Sal Bank in the Straits of Florida in an attempt to evade any observers.

To throw any pursuers off his trail, Köhler broadcast a message in the open that he intended to call at Tampico, Mexico on 4 August.

[6] On the night of 3/4 August, Karlsruhe received word of the state of war between Germany and France, and the greatly increased risk of conflict with Britain.

Karlsruhe's standing orders in the event of war were to conduct a commerce raiding campaign against British merchant traffic.

[6] Dresden was still present in the region at the outbreak of World War I at the end of July,[7] which complicated the British attempt to hunt down the German cruisers.

[8] On 6 August, Karlsruhe rendezvoused with Kronprinz Wilhelm about 120 nmi (220 km; 140 mi) north of Watling Island.

Karlsruhe was in the process of transferring guns and equipment to the liner when Craddock, in his flagship HMS Suffolk, appeared to the south.

Karlsruhe's faster speed allowed her to quickly outpace Craddock, but at 20:15, Bristol joined the pursuit and briefly fired on the German cruiser.

The British failed to relocate her, and by 9 August, Karlsruhe reached Puerto Rico with only 12 tons of coal in her bunkers.

Over the course of 21–23 August, the ship went to Maraca island south of the mouth of the Amazon River to replenish her coal stocks from a German steamship.

The ship used the cover of a major storm to slip through the British blockade of the North Sea, and put in at Ålesund, Norway.