"Twelvers"

"Twelvers" is another term for the Shia Muslims of Iran and Iraq. That's
because there were 12 "secret" Imams or holy religious leaders of Shia Islam,
who lived "underground," because Shi'ism was considered a heretical sect of
Islam, and so they were persecuted and their leaders would have been killed
by the majority Sunni Muslims if they had been caught. It's as if in
Christianity the early Protestant religious leaders would have been forced to
live "underground." Certainly there have been many Catholic-Protestant
clashes before the two settled into a harmonious co-existence (but not in
Northern Ireland). (Of course, there are some Shia such as the Ismailis, who
don't accept all the 12 as holy, only 7 of them, and they are of course called
'Seveners.'
The Shias believe that Mohammed's son-in-law, the Imam Ali who married
his daughter Fatima, were the rightful heirs to his political/religious
domain, and not the Caliphs who were elected or selected by a small group of
powerful religious-political leaders. When Hussein the son of Ali and Fatima,
and hence Mohammed's grandson, was defeated in the battle of Karbala in
Iraq in 680, the Shia became a persecuted minority, still believing in the
rightful rule of Ali-Hussein and their descendents of the so-called Fatimid
line.
Their leadership was replaced by the secret Imams, the last of whom
disappeared in 880. Ever since then the Twelvers have been awaiting his
return (as their Messiah). That is why the destruction of the golden-domed
Mosque in Samarra in Iraq is such a blow to Shia Islam, because most of
the original secret Imams were buried there. There is no doubt that this
action was taken by Sunni extremists to reignite the age-old clash between
Sunni and Shia Islam.
There are two approaches the West could take to this. The first is "let them
fight it out," its not our problem. This would certainly have consequences,
because although the Shia in Iraq are a majority compared to the Sunni, they
do not have the military experience and capability of the Sunnis. Also, Iran
is nearby and would probably not allow the Iraqi Arab Shia to be defeated by
the Sunnis. This might ignite a conflagration with the whole Sunni majority
of the Middle East, not a good prospect.
The US is right in the middle of this dispute, trying desperately to hold the
two sectarian groups together in a united and "democratic" Iraq. Even if its
possible, which seems unlikely, they have an almost impossible task while the
Sunni-led insurrection continues and the Shia reaction to it grows ever
stronger. The Shia have already torched 8 Sunni mosques in retaliation and
internecine killing has begun. However, if in the face of this conflict the
US is forced to withdraw from Iraq it would no doubt be viewed as a major
defeat for the US and for the forces supporting democracy. Thus is the future
of our world bound up in an arcane struggle for ancient succession.