Question: When did the invasion last in which the human shield action to Iraq was a strategy to prevent bombings of certain locations?

Context paragraphs:
Earth mysteries: Earth mysteries are a wide range of spiritual, quasi-religious and pseudoscientific ideas focusing on cultural and religious beliefs about the Earth, generally with regard to particular geographical locations of historical significance.  Believers in Earth mysteries generally consider certain locations to be "sacred", or that certain spiritual "energies" may be active at those locations.  The term "alternative archaeology" has also been used to describe the study of Earth mystery beliefs.

Superconvergence: In numerical analysis, a superconvergent or supraconvergent method is one which converges faster than generally expected ("superconvergence" or "supraconvergence").  For example, in the Finite Element Method approximation to Poisson's equation in two dimensions, using piecewise linear elements, the average error in the gradient is first order.  However under certain conditions it's possible to recover the gradient at certain locations within each element to second order.

2003 invasion of Iraq: The 2003 invasion of Iraq lasted from 20 March to 1 May 2003 and signalled the start of the Iraq War, which was dubbed Operation Iraqi Freedom by the United States (prior to 19 March, the mission in Iraq was called Operation Enduring Freedom, a carryover from the War in Afghanistan).  The invasion consisted of 21 days of major combat operations, in which a combined force of troops from the United States, the United Kingdom, Australia and Poland invaded Iraq and deposed the Ba'athist government of Saddam Hussein.  The invasion phase consisted primarily of a conventionally fought war which included the capture of the Iraqi capital of Baghdad by American forces with the implicit assistance of the United Kingdom, alongside Australia and Poland.

Ruth Russell: Ruth Elizabeth Russell (born 6 March 1946) is an Australian peace activist, and one of five Australian citizens who travelled to Iraq in 2003 to function as a human shield, and for some of the eight weeks was located at the Taji food silo.  Her stated reason for doing so was to show "solidarity with the Iraqi civilians who will suffer greatly from the planned invasion of Iraq".

Human shield action to Iraq: Human shield action to Iraq was a group of people who travelled to Iraq to act as human shields with the aim of preventing the U.S.-led coalition troops from bombing certain locations during the 2003 invasion of Iraq.

Kenneth O'Keefe: Kenneth Nichols O'Keefe (born July 21, 1969) is an American-Irish-Palestinian citizen and activist and former United States Marine and Gulf War veteran.  In 2001 he set fire to his United States passport. <ref name="https://www.youtube.com/watch?v=9OMHlEpW9mI"> </ref><ref name="http://www.guardian.co.uk/world/2010/jun/07/israel-kills-four-palestinians-gaza"> </ref><ref name="http://news.bbc.co.uk/2/hi/uk_news/2664297.stm"> </ref> Subsequently, he led the human shield action to Iraq and was a passenger on the MV "Mavi Marmara" during the Gaza flotilla raid.  He participated during clashes on the ship including the attacking of two Israeli commandos.

Human Shield (political party): Human Shield (Croatian: "Živi zid" , literally translated as "Living Wall") is a populist political party in Croatia, formed out of an anti-eviction group of the same name.  Also known as Human Blockade, the group fights foreclosures by occupying property and forming a "human shield", hence the name.

Ivan Pernar (Croatian politician): Ivan Pernar (born 14 October 1985) is a Croatian politician and anti-eviction activist.  In June 2011, he founded the Alliance for Change party, which later became Human Shield.  He is a member of Croatian Parliament since the 2016 elections, being elected in the 6th electoral district on the joint party list of Human Shield, Let's change Croatia and Youth Action.

Police car: A police car (also called a police cruiser, cop car, prowler, squad car, radio car or radio mobile patrol (RMP) ) is a ground vehicle used by police for transportation during patrols and to enable them to respond to incidents.  Typical uses of a police car include transporting officers so they can reach the scene of an incident quickly, transporting and temporarily detaining suspects in the back seats, as a location to use their police radio or laptop or to patrol an area, all while providing a visible deterrent to crime.  Some police cars are specially adapted for certain locations (e.g. traffic duty on busy roads) or for certain operations (e.g. to transport police dogs or bomb squads).  Police cars typically have rooftop flashing lights, a siren, and emblems or markings indicating that the vehicle is a police car.  Some police cars may have reinforced bumpers and alley lights, for illuminating darkened alleys.

Human shield: Human shield is a military and political term describing the deliberate placement of non-combatants in or around combat targets to deter the enemy from attacking these combat targets.  It may also refer to the use of persons to literally shield combatants during attacks, by forcing them to march in front of the combatants.

Supporting paragraphs: Human shield action to Iraq 2003 invasion of Iraq
Answer: 20 March to 1 May 2003