Why doesn't my trigger put data into my table? When I execute my trigger, it says it executed commands, but there is still no data in the tAttackPlan where it is supposed to insert data into. Can not figure out why.

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

IF OBJECT_ID ('trAttack', 'tr') IS NOT NULL
    DROP TRIGGER trAttack
GO
CREATE TRIGGER trAttack
   ON tAttackPlan
   AFTER INSERT, UPDATE
AS 
BEGIN

    SET NOCOUNT ON;
    DECLARE @AttackRequirementID INT, @MinionID INT, @DomainID INT, @MinimumCount INT, @Count INT, @MinionID_min INT
    SELECT @DomainID = (SELECT @DomainID FROM inserted)
    SELECT @Count = (SELECT SUM(Count) FROM tCensus GROUP BY MinionID)
    SELECT @MinionID_min = tMinion.MinionID
    FROM dbo.tMinion 
    INNER JOIN dbo.tCensus ON dbo.tMinion.MinionID = dbo.tCensus.MinionID 
    CROSS JOIN dbo.tAttackRequirement 
    CROSS JOIN dbo.tAttackPlan 
    INNER JOIN dbo.tDomain ON dbo.tAttackPlan.DomainID = dbo.tDomain.DomainID

    INSERT INTO tAttackPlan (DateOfAttack, DomainID)
    VALUES (1050, @DomainID)

    IF @Count &lt; @MinimumCount
        RAISERROR ('There are not enough minions to attack', 16, 10)
END
GO
What learning_DBAdmin is saying makes sense... 
if this is the only script you are running, it will only create the trigger... 
when you insert or update the table tAttackPlan, it will trigger the trAttack trigger. 

Now let's analyze the trigger... If an insert or update is done on the tAttackPlan table the trigger will insert into tAttackPlan the attack date and domainID... Is this what you really want? It seems to be recursive to me but not sure of the whole story behind this piece of code. ... What I see is if your trigger is triggered it will insert into the tAttackPlan table which will trigger the trAttack again, and so on and so forth. 

Also, note that a trigger has 2 internal tables inserted and deleted, which define the new value of the insert/update (in inserted) and the old value or records to delete (in deleted)... 

Please check Microsoft sites to see how triggers work.