There is a legent that says, during the late 1700 when Napoleon was
having alot of wars in Europe. A war between Sweden and San Marino was
decleared but when Napoleon deceased the war was all forgotten and
never ended until these days. Some say the war never existed. Some say
Sweden are still at war with San Marino. Could  you please bring some
clarity to this question?

Dear blh42,

I am sorry to say that there is nothing true about this story. I also
found a variant of it, claiming that San Marino and Sweden had been
formally at war since the mid-17th century because San Marino had been
allied with countries that fought Sweden in the Thirty Years' War
(1618-1648), but did not sign the Peace Treaty of Westphalia since it
had not participated in any military action. Therefore, this version
of the legend says, San Marino and Sweden have stayed in a formal
state of war until 1996, when the two nations officially declared the
war ended. This version can even be found in sources like the
Microsoft Encarta Encyclopedia:
http://au.encarta.msn.com/text_761565721___0/San_Marino_(country).html

However, neither that version nor the variant connected with the
Napoleonic Wars is true. It is only an amusing popular myth, as
Swedish historian Ulf Sundberg explained in his 1997 book "Svenska
freder och stillestånd 1249-1814". The myth about the almost endless
war between Sweden and tiny San Marino completely ignores the fact
that neutral San Marino has not been involved in any conflicts since
1463.

Ulf Sundberg's text on the myth of the Swedish-San Marinese war can be
found, for example, on the website of the Swedish Library of Military
History (unfortunately, only in Swedish):
http://www.smb.nu/svenskakrig/freder/san_marino.asp

I hope this answers your question!
Regards,
Scriptor



Sources:

Swedish Library of Military History: Freden med San Marino
http://www.smb.nu/svenskakrig/freder/san_marino.asp

Timelines of History: Timeline Germany to 1820
http://timelines.ws/countries/GERM_TO_1820.HTML

Wikipedia: San Marino
http://en.wikipedia.org/wiki/San_Marino

Decades.com: History Search
http://rcm.amazon.com/e/cm?t=decades-20&p=8&o=1&l=ez&f=ifr


Search terms used:
"san marino" svezia guerra
://www.google.de/search?hl=de&newwindow=1&c2coff=1&q=%22san+marino%22+svezia+guerra&btnG=Suche&meta=
"san marino" sweden "thirty years war" 1996
://www.google.de/search?q=%22san+marino%22+sweden+%22thirty+years+war%22+1996&hl=de&lr=&newwindow=1&c2coff=1&start=0&sa=N
"san marino" svenska 
://www.google.de/search?hl=de&newwindow=1&c2coff=1&q=%22san+marino%22+svenska&btnG=Suche&meta=
Sverige krig "San Marino" 1996
://www.google.de/search?hl=de&newwindow=1&c2coff=1&q=Sverige+krig+%22San+Marino%22+1996&btnG=Suche&meta=
sweden "san marino" war
://www.google.de/search?hl=de&newwindow=1&c2coff=1&q=sweden+%22san+marino%22+war&btnG=Suche&meta=

I think the town of Berwick-upon-Tweed was at war with Russia until
the mid-1980s... not thats any use to you....