'Pekin' was a Polish naval operation in which the destroyers Burza, Błyskawica and Grom escaped from Poland to the UK (29 August/1 September 1939).

In the event of an imminent war with Germany, the captains of the three ships had been ordered to steam to British ports and assist the Royal Navy. The plan was successful and allowed the ships to avoid certain destruction in the German invasion. The rationale of the plan was to remove the Dywizjon Kontrtorpedowców (destroyer division) of the Polish navy from the Baltic Sea as the Kriegsmarine had a significant numerical advantage over the Polish navy, and Polish high command appreciated that in the event of war any Polish ships remaining in the small and essentially landlocked Baltic Sea were likely to be sunk or captured by the Germans. Also, the escape route through the Kattegat and Skagerrak between Denmark in the south and Sweden and Norway in the north lay well within the operational range of the Kriegsmarine and Luftwaffe, so there was little chance for the plan to succeed if it was launched after the outbreak of war.

As the tension between Poland and Germany became more acute in August, Wiceadmirał Józef Unrug, commanding the Polish fleet, authorised the operation on 26 August, a day after the signature of the Polish-British Common Defence Pact, and the executive order was issued on 29 August by Marszałek Polski Eduard Śmigły-Rydz, the Polish commander-in-chief. The ships departed at 14.15 on the same day under the command of Komandor porucznik Roman Stankiewicz.

It had been ordered that in the event that German ships were encountered, Burza, the oldest and smallest of the three ships, was to fight a delaying action and thereby facilitate the escape of the two newer and larger destroyers.

Shortly after leaving port, the Polish ships were sighted by U-31 to the north of Hel, and later encountered the German destroyers Bruno Heidemann, Erich Steinbrinck, Friedrich Eckholdt and Friedrich Ihn on patrol between the Bay of Danzig and the Danish island of Bornholm, but no action followed. The ships steamed without hindrance to the west through the Baltic, entering the Oresund after 24.00. Farther on their passage, the Polish destroyers encountered the German light cruiser Königsberg and a destroyer, but as the war had not started there was no combat. Next the Polish ships passed through the Kattegat and Skagerrak. During 31 August the ships were spotted and followed by German reconnaissance seaplanes, and during the night the three destroyers altered course toward Norway in an effort to shake off the pursuit, after which they returned to their original course toward the UK. The ships entered the North Sea, and at 09.25 were informed that the German 'Weiss' (i) invasion of Poland had started.

At 12.58 the Polish destroyers encountered the British destroyers Wanderer and Wallace, and a British liaison officer joined the Polish squadron. At 17.37 the Polish destroyers docked near Edinburgh.

'Pekin' generated controversy in Poland, but was in fact an entirely sensible course of action. The ships then served alongside the Royal Navy for the remainder of the war, which Burza and Błyskawica survived.

All of the Polish ships remaining in the Baltic were engaged by the German forces, initially in the Battle of Gdańsk Bay on 1 September, and were sunk or captured. The fate of the two largest remaining ships is telling: the fourth Polish destroyer, Wicher, and the largest ship of the Polish navy, the heavy minelayer Gryf, had both been sunk by 3 September.

In the face of 'Pekin', on August 30 the Germans recalled from the Baltic Sea the tactical unit of Vizeadmiral Hermann Densch, the Befehlshaber der Aufklärungsstreitkräfte (commander of scouting forced), which had been tasked with their engagement and destruction, namely the light cruisers Nürnberg, Köln and Leipzig which constituted half of Densch’s light cruiser strength.